
<PAGE>
 
                                  B Y L A W S

                                      of

                              CRITICAL PATH, INC.
                      (Effective as of January __, 1999)


                                  ARTICLE I 
                                 
                               Principal Office

     Section 1.   Principal Office.  The Board of Directors shall fix the
location of the principal executive office of the corporation at any place
within or outside the State of California. If the principal executive office is
located outside California and the corporation has one or more business offices
in California, then the Board of Directors shall fix and designate a principal
business office in California.

     Section 2.   Other Offices.  The Board of Directors may at any time
establish branch or subordinate offices at any place or places.



                                  ARTICLE II
                             
                           Meetings of Shareholders
                           
     Section 1.   Place of Meetings.  All meetings of the shareholders shall be
held at any place within or without the State of California which may be
designated by the board of directors. In the absence of any such designation,
shareholders' meetings shall be held at the principal executive office of the
corporation.

     Section 2.   Annual Meetings.  An annual meeting of shareholders shall be
held each year on a date and at a time designated by the Board of Directors. At
that meeting, directors shall be elected. Any other proper business may be
transacted at the annual meeting of shareholders.

     Section 3.   Special Meetings.  Special meetings of the shareholders may be
called by the board of directors, the chairman of the board, the chief executive
officer and president, or by the holders of shares entitled to cast not less
than ten percent (10%) of the votes at the meeting. Notice of any special
meeting shall specify the general nature of the business to be transacted, and
no other business may be transacted at such meeting. Upon receipt of a written
request addressed to the chairman, chief executive officer and president, vice
president or secretary, mailed or delivered personally to such officer by any
person (other than the board) entitled to call a special meeting of
shareholders, such officer shall cause notice to be given, to the shareholders
entitled to vote, that a meeting will be held at a time requested by the person
or persons calling the meeting, not less than thirty-five (35) nor more than
sixty (60) days after the receipt of such request. If such notice is not given
within twenty (20) days after receipt of such request, the persons calling the
meeting may give notice thereof in the manner provided by

                                       1
<PAGE>
 
these bylaws or apply to the superior court as provided in the California
General Corporation Law.

     Section 4.   Procedure of Annual Meeting; Notice of Meetings.  To be
properly brought before the annual meeting, business must be either (a)
specified in the notice of meeting (or any supplement thereto) given by or at
the direction of the Board of Directors, (b) otherwise properly brought before
the meeting by or at the direction of the Board of Directors, or (c) otherwise
properly brought before the meeting by a shareholder of record. In addition to
any other applicable requirements, for business to be properly brought before
the annual meeting by a shareholder, the shareholder must have given timely
notice thereof in writing to the Secretary of the Corporation. To be timely, a
shareholder's notice must be delivered to or mailed and received at the
principal executive offices of the Corporation, addressed to the attention of
the Secretary of the Corporation, within 120 calendar days before the date of
the Corporation's proxy statement released to shareholders in connection with
the previous year's annual meeting. A shareholder's notice to the Secretary
shall set forth as to each matter the shareholder proposes to bring before the
annual meeting (i) a brief description of the business desired to be brought
before the annual meeting, (ii) the name and record address of the shareholder
proposing such business, (iii) the class and number of shares of the Corporation
which are beneficially owned by the shareholder, and (iv) any material interest
of the shareholder in such business. Notwithstanding anything in these by-laws
to the contrary, no business shall be conducted at the annual meeting except in
accordance with the procedures set forth in this Section 4; provided, however,
that nothing in this Section 4 shall be deemed to preclude discussion by any
shareholder of any business properly brought before the annual meeting.

Written notice of each meeting of the shareholders, annual or special, shall be
given to each shareholder entitled to vote thereat not less than ten (10) days
nor more than sixty (60) days before the date of the meeting. Such notices shall
be given personally or by first-class mail or other means of written
communication permitted by the California General Corporation Law, charges
prepaid, addressed to each shareholder at the address appearing on the books of
the corporation, or given by the shareholder to the corporation for the purpose
of notice. If no address of a shareholder appears on the books of the
corporation or is given by the shareholder to the corporation, notice is duly
given to him or her if sent by mail or other means of written communication
addressed to the place where the principal executive office of the corporation
is located or if published at least once in a newspaper of general circulation
in the county in which said principal executive office is located. Any such
notice shall be deemed to have been given at the time when delivered personally
or deposited in the United States mail or sent by other means of written
communication.

     Such notices shall state (i) the place, date and hour of the meeting, (ii)
those matters which the board, at the time of the mailing of the notice, intends
to present for action by the shareholders, (iii) if directors are to be elected,
the names of nominees intended at the time of the notice to be presented by
management for election, and (iv) such other matters, if any, as may be
expressly required by statute.  In addition, in the case of a special meeting,
the general nature of the business to be transacted shall be set forth in the
notice, and no other business may be transacted.

     Section 5.   Quorum.  The presence in person or by proxy of the holders of
[66 2/3%] of 

                                       2
<PAGE>
 
then pricing for the POP service shall be based on CP's prices for a POP service
(as calculated under Section 6.2 hereof) and not on the prices utilized for
services that are not primarily a POP service.

     (e)  Delivery and Acceptance.  Following the completion of the development
          -----------------------                                              
and internal testing of any version of the ICQ Mail Service, CP shall deliver
such version to ICQ for evaluation and acceptance.  ICQ shall have thirty (30)
days following such delivery by CP to evaluate whether such version both (i)
functions properly (i.e., in accordance with specifications, including, in the
case of the initial version, the Specifications set forth in Exhibit B, without
Severity 1 or Severity 2 Problems and without materially disrupting the
operation of other applications or the relevant operating system), and (ii)
satisfactorily incorporates the modifications to the user interface, features
and functions requested by ICQ.  If ICQ reasonably determines that any such
version of the ICQ Mail Service either (i) does not function properly, or (ii)
does not satisfactorily incorporate the modifications requested by ICQ, ICQ may
reject such version by providing CP with written notice within such **** period
specifying in detail the reason for rejection.  Any version of the ICQ Mail
Service that has not been rejected within such **** period shall be deemed
accepted.  If ICQ rejects any version of the of the ICQ Mail Service, CP shall
as promptly as commercially possible but in any case within **** following ICQ's
notice of rejection, correct, to the reasonable satisfaction of ICQ, the
deficiencies in such version that were specified in ICQ's notice of rejection.
The failure to correct such deficiencies to the reasonable satisfaction of ICQ
within such **** period shall constitute a material breach of this Agreement by
CP.

     (f)  Assistance from ICQ.  ICQ shall provide CP with reasonable 
          -------------------   
consultative assistance in connection with the development obligations of CP
as set forth in this Section 2.1. In addition, during the term of this
Agreement, ICQ agrees to notify CP in advance of any modifications and/or
changes to the ICQ System through which the ICQ Mail Service is provided that
ICQ believes may result in incompatibility between the parties' respective
systems or interruptions in the ICQ Mail Service (including without
limitation, network configuration changes and system maintenance), as well as
upgrades and removal of devices that impact the production and network
connectivity from, ICQ's system through which the ICQ Mail Service is
provided. The parties will work together to resolve any such potential and
actual incompatibility or interruptions in connection with ICQ's
implementation of any such change and/or modification.

2.2  ICQ Mail Website.
     ---------------- 

     (a)  Development and Control.  The parties shall design and develop the
          -----------------------                                           
collection of Internet webpages that shall serve as the location at which ICQ
Mail Users are able to access and use the ICQ Mail Service (the "ICQ Mail
Website"); provided that ICQ shall control all aspects of the design,
development and functionality of the ICQ Mail Service, including the ICQ Mail
Website, and all content on, and navigational elements of, the ICQ Mail Service,
subject to the technical limitations and design requirements of the CP Service
and CP System (which shall themselves remain subject to the Specifications and
other requirements outlined hereunder).  The ICQ Mail Website will be branded as
provided in Section 3.1, and all pages will be situated on ICQ URLs owned by ICQ
(e.g., http://www.icq.com/icqmail).

     (b)  Hosting by CP.  Except as otherwise provided in Section 2.1(c), the 
          -------------   
ICQ Mail Website (and the relevant host portions of the ICQ Mail Service)
shall be physically hosted on servers maintained by CP and located at CP's
principal operational center in San Francisco, California, provided that, as
may from time to time become appropriate so as to meet the performance
requirements set forth in Section 2.4 and Exhibits B and C, CP may expand its
hosting locations to other locations, including international locations. ICQ
and CP will work together to determine expanded hosting requirement

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           3
<PAGE>
 
consistent with the foregoing, and ICQ will provide reasonable assistance in
connection with CP's implementation of other hosting locations.  During the
period that the ICQ Mail Website (and the relevant host portions of the ICQ
MailService) is hosted by CP, CP shall comply with all  hosting, administrative
obligations and reporting requirements required to perform its obligations
hereunder, including without limitation those set forth on Exhibits B and C and
shall cause the ICQ Mail Service to comply with the requirements set forth on
Exhibits B and C.

     (c)  ****.  Notwithstanding the provisions of Section 2.2(b), **** may
exercise in its discretion at any time during the term of this Agreement
(including prior to ****), to **** of the **** (and the relevant ****) to ****
located at location(s) **** exercise this option by providing **** written
notice of its wish ****.  The parties shall then work together **** as soon as
reasonably possible, but in any event within ninety (90) days following the
receipt of such notice ****.  In carrying out ****, the parties shall work
together to minimize **** in ****.  If, in the course of the parties' good faith
**** determines that **** will not be technologically possible or will not be
****, then **** or (if applicable) ****, and thereafter **** have all ****
responsibilities for **** as provided herein.  If **** it option **** shall
provide **** sufficient **** to remotely perform its administrative functions
and other obligations with respect to **** (or other access necessary to ****
such functions and obligations).  Upon any such **** administrative and
reporting requirements under Exhibit C shall be modified as specified on Exhibit
C.

2.3  Premium Services.
     ---------------- 

     (a)  Core Premium Services.  As part of the operation of the ICQ Mail
          ---------------------                                           
Service: (i) CP will make the Core Premium Services available to ICQ for ICQ to
offer to ICQ Mail Users; and (ii) ICQ shall offer such services in connection
with ICQ Mail Service at its option with the particular placement and method of
integration of the Core Premium Services into the ICQ Mail Service to be at the
discretion of ICQ.  In accordance with the provisions of Section 2.1, CP shall
develop or modify the ICQ Mail Service, as necessary or appropriate, to support
the provision of the Core Premium Services as specified by ICQ.

     (b)  Expanded Premium Services. CP shall, at its expense, create Updates to
          -------------------------                                             
the ICQ Mail Service from time to time so as to keep the ICQ Mail Service
competitive with other web-based e-mail services as required by Section 2.4,
including the creation of Expanded Premium Services.  As part of the operation
of the ICQ Mail Service, ICQ may, but shall not be required to, offer one or
more Expanded Premium Services to ICQ Mail Users.  Such Expanded Premium
Services may include services offered by ICQ, CP or any third party.  In
accordance with the provisions of Section 2.1, CP shall, upon the request of
ICQ, develop or modify the ICQ Mail Service, as necessary or appropriate, to
create, or support the provision of, Expanded Premium Services in the manner
specified by ICQ.

     (c)  Pricing of Premium Services. ICQ shall, in its discretion, determine
          ---------------------------                                         
the pricing, if any, to be charged to ICQ Mail Users for the right to use any
Core Premium Services and/or Expanded Premium Services.  ICQ shall pay CP in
respect of premium services only as indicated in Section 6.5 below.

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           4
<PAGE>
 
2.4  Competitive Performance Standards.  Throughout the term of this Agreement,
     ---------------------------------                                         
CP shall take all steps reasonably necessary to ensure that, except to the
extent otherwise agreed by ICQ, the ICQ Mail Service shall provide ICQ Mail
Users with a set of features and functions that is, in ICQ's reasonable
judgment, at least as good (in terms of the number and types of features and
functions and the quality thereof) as the features and functions then available
through the best other web-based email service providers listed in the attached
Exhibit G ("Other Webmail Service Providers").  ICQ shall have the right from
time to time by written notice to CP to modify the list of Other Webmail Service
Providers from time to time to reflect the then-leading web-based email service
providers as determined in ICQ's reasonable judgment.  Further, CP shall take
all steps reasonably necessary to ensure that the performance of the ICQ Mail
Service is at least as good as the performance of the web-based email services
of the Other Webmail Service Providers and otherwise complies with the
performance requirements set forth on Exhibit C.  In furtherance of the **** of
this Section 2.4, the parties agree to discuss from time to time the development
of **** into the ICQ Mail Service.

2.5  Other Modifications.  Notwithstanding anything to the contrary contained
     -------------------                                                     
herein, ICQ reserves the right to redesign and/or modify the organization,
structure, "look and feel," navigation, features and other elements of the ICQ
Service and the ICQ Mail Service, subject to the technical limitations and
design requirements of the CP Service and CP System (which shall themselves
remain subject to the Specifications and other requirements outlined hereunder).

3.   Product Branding and Other Promotional Obligations

3.1  Product Branding.  All components of the ICQ Mail Service, the ICQ Mail
     ----------------                                                       
Website and all client components of the ICQ Mail Service that are integrated
into the ICQ Client shall be branded in ICQ's sole discretion and shall not
include any other branding.  Despite the foregoing, ****.  All aspects of such
recognition shall be determined by ICQ, including placement, size, and look and
feel (subject to any applicable trademark usage guidelines provided by CP with
respect to any of its marks that are used in such recognition other than those
that relate to size and placement).  ICQ shall not have any obligation with
respect to any particular promotion of the ICQ Mail Service or placement of the
ICQ Mail Service within the ICQ Service or elsewhere, including relative to any
other email service or provider.

3.2  Promotion of ICQ Service by CP.  CP shall use commercially reasonable
     ------------------------------                                       
efforts to promote the ICQ Service to its customers and partners and to persuade
such customers and partners to adopt the ICQ Service as an integrated component
of the email products and services provided to such customers and partners by
CP.  Without limiting the foregoing, CP will ****   ICQ shall assist CP, as
reasonably appropriate, in such promotional efforts, including by making
available to CP the addresses need for the application modifications described
in subpart (b) above.  In addition, in the event CP provides its own email
service (i.e., one not offered on behalf of a third party), CP will as soon as
practicable integrate the ICQ Service into such email service.

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           5
<PAGE>
 
4.   ICQ Mail User Registration and Information

4.1  Ownership of Assets and Customer Relationships.  ICQ shall own all goodwill
     ----------------------------------------------                             
and tangible and intangible assets and aspects of the ICQ Mail Service and the
ICQ Mail Website, including all materials provided by ICQ to CP for the purpose
of branding the ICQ Mail Service and the ICQ Mail Website ("ICQ Branding
Materials")and of the entire relationship with ICQ Mail Users, including without
limitation, all aspects of such relationship specified in this Section.  Despite
the foregoing, ICQ has no rights to or ownership of the CP System (including the
CP Email Software or ICQ Mail Software) or the CP Service, as further provided
in Section 12.2, except for the contractual rights expressly provided hereby.

4.2  User Registration.  In order to use the ICQ Mail Service, an ICQ User will
     -----------------                                                         
be required to register for the ICQ Mail Service.  ICQ shall determine, in its
sole discretion, any agreements to be obtained from and/or information to be
collected from the ICQ User as part of the registration process and any domain
names, email addresses and passwords to be assigned and/or used with the ICQ
Mail Service.  Despite the foregoing, ICQ will indemnify CP against any loss,
liability or expenses that CP incurs based on any claims made against CP by a
user of the ICQ Mail Service or by any third party to the extent that CP can
demonstrate that either such claim would not have prevailed or CP would have
been indemnified by the user, had ICQ entered into an agreement with the
applicable user(s) consistent with, and providing no less protection to CP, than
the Acceptable Use Policy and Terms of Use attached hereto as Exhibit F.
Registration for the ICQ Mail Service shall take place at the ICQ Mail Website
or at such other location as may be specified by ICQ.  The billing and
collection of any fees or other amounts to be charged to ICQ Mail Users from
time to time (including, if applicable, fees for the use of the basic ICQ Mail
Service or for the use of any Core Premium Services or Expanded Premium
Services) shall be performed by ICQ and CP shall not directly contact or
communicate with ICQ Mail Users except with the express consent in writing of
ICQ to so do, which consent must be obtained for each contact or communication.

4.3  ICQ User Information and Solicitation
     -------------------------------------

     (a)  Ownership of ICQ User Information.  ICQ shall own any and all 
          ---------------------------------   
information collected from ICQ Members in connection with the ICQ Mail
Service, including information collected during the registration processes for
the ICQ Service and the ICQ Mail Service, respectively, and information then
or subsequently obtained from any use of the ICQ Service and/or the ICQ Mail
Service, including without limitation all information relating to ICQ User
names, passwords, ICQ numbers, email addresses, domain names (including vanity
domain names), addresses, credit card information, user preferences or history
or other identifying information (collectively, "User Information"). All User
Information shall be deemed Confidential Information of ICQ. CP agrees, both
during and after the term of this Agreement (and despite any provisions of
Sections 4.3(b) or 4.3(c)), not to use any User Information for any purpose
other than the operation of the ICQ Mail Service or to disclose any such
information to any third party without the prior written consent of ICQ, which
consent may be granted or withheld in ICQ's sole and absolute discretion,
provided that CP may access and disclose User Information solely as necessary
to comply with applicable laws, regulations and government orders or requests
or to protect CP's or its customers' or partners' rights or property, provided
that CP uses all reasonable efforts to limit any such disclosure to the
minimum required and not to use such information except for such purposes and
provides ICQ with as much advance written notice of CP's intended use or
disclosure as is practicable. CP will at all times comply with all privacy
policies that ICQ or AOL may implement and provide to CP from time to time
with respect to the ICQ Service, the ICQ Mail Service and/or User Information,
subject to CP's rights with respect to the User Information as provided
hereunder.


CONFIDENTIAL EXECUTION COPY           6
<PAGE>
 
     (b)  No Competitive Solicitation.  During the term of this Agreement and 
          ---------------------------          
for the two-year period following the expiration or termination of this
Agreement (and without limiting any other provision of this Agreement,
including Section 4.3(a)), neither CP nor its agents shall use the ICQ Service
or the ICQ Mail Service to (i) solicit or participate in the solicitation of
ICQ Users when that solicitation is for the benefit of any entity (including
CP) which could reasonably be construed to be or to become in competition with
ICQ, including without limitation with the ICQ Service or the ICQ Mail
Service, or (ii) promote any services or products which could reasonably be
construed to be in competition with services or products provided by ICQ,
including without limitation, the ICQ Service and the ICQ Mail Service.
Nothing in this Section 4.3(b) shall be construed to prohibit CP from
soliciting, promoting, or providing the CP Service to any third party, whether
during the term of this Agreement or thereafter, provided that CP complies
with the terms of Section 9 (Exclusivity) during the term of this Agreement
and Section 13 (Confidential Information) at all times.

     (c)  No Communication.  During the term of this Agreement and for the two-
          ----------------                                                    
year period following the expiration or termination of this Agreement (and
without limiting any other provision of this Agreement, including Section
4.3(a)), CP agrees not to send any ICQ User any messages or communications on or
through the ICQ Service or the ICQ Mail Service, unless (i) CP has a Prior
Business Relationship with such ICQ User, and (ii) such message or communication
complies with the applicable end-user agreement for the ICQ Service or the ICQ
Mail Service, any standard privacy policies for the ICQ Service or the ICQ Mail
Service and all applicable laws and regulations.  For purposes of the foregoing,
a "Prior Business Relationship" shall mean that the ICQ User has either (i)
purchased products or services from CP, or (ii) voluntarily provided information
to CP (other than as a result of being an ICQ Mail User) through a contest,
registration, or other communication, which included clear and conspicuous
notice to the ICQ User that the information provided by the ICQ User could
result in a message or communication being sent to that ICQ User by CP or its
agents.

5.   Technical Support

ICQ shall provide all frontline technical and customer support to ICQ Mail Users
who have problems with, or questions concerning, the installation, use,
operation or maintenance of the ICQ Mail Service, all in such manner as ICQ
determines in its sole discretion.  CP shall, at no cost to ICQ, provide to ICQ
the back-end support and training and support regarding the ICQ Mail Service
specified on Exhibit D.

6.   Revenue Provisions

6.1  Net Advertising Revenue for Standard Email Services.
     --------------------------------------------------- 

     (a)  Revenue Sharing.  During the term of this Agreement, subject to the
          ---------------                                                    
volume reductions specified in Section 6.1(b), ICQ agrees to pay CP **** of the
Net Advertising Revenue (as defined in Section 6.1(c)) that is actually
collected by ICQ for each calendar quarter during the term of this Agreement in
which the ICQ Mail Service is operational.

     (b)  Volume Reductions.  The percentage of Net Advertising Revenue that is
          -----------------                                                    
payable to CP pursuant to Section 6.1(a) shall be reduced by **** per each block
of **** Active ICQ Mail Users during such quarter (but excluding the first such
block of **** Active ICQ Mail Users), up to a maximum reduction of ****
(resulting in a percentage of Net Advertising Revenue to CP of ****.  For
example, if in Q1 the **** Mail Users is ****, then the **** Net Advertising
Revenue payable to CP for such quarter would be **** Active ICQ Mail Users,
after the first such block of **** Active ICQ Mail Users).  If, however, in Q2,
the **** Mail Users

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           7
<PAGE>
 
increases to ****, then the **** of Net Advertising Revenue payable to CP for
such quarter would be **** Active ICQ Mail Users after the first such block, but
subject to the maximum reduction of twenty percentage points from the initial
split to CP.

     (c)  Definition of Net Advertising Revenue.  For purposes of this 
          -------------------------------------  
Agreement, "Net Advertising Revenue" shall mean, for any calendar month, (i)
the gross revenue received by ICQ from the sale of electronic advertisements
during such month that are displayed on screens of the ICQ Mail Website or
within the ICQ Client that in either case are dedicated primarily to the
implementation of Standard Email Services through the ICQ Mail Service (such
as the welcome page of the ICQ Mail Website, or pages whose primary functions
are to read/write/send or modify settings), less (ii) the actual agency fees
incurred by ICQ in connection with the placement of such electronic
advertisements (or, if no such agency fees were incurred, **** of the gross
revenues received by ICQ for such electronic advertisements). For purposes of
clarification, "Net Advertising Revenue" shall not include any revenues
received by ICQ from the sale of advertisements (i) on any pages of the ICQ
Mail Service or ICQ Mail Website that do not pertain primarily to the
implementation of Standard Email Services (including screens that simply
include links or buttons to Standard Email Services) or (ii) on any screens of
the ICQ Client that are not dedicated primarily to the provision of Standard
Email Services through the ICQ Mail Service.

     (d)  Ownership of Advertising.  The right of CP to participate in the Net
          ------------------------                                            
Advertising Revenue pursuant to the provisions of this Section 6.1 shall in no
way create any ownership interest in CP with respect to ICQ advertising
inventory.  ICQ owns all right, title and interest in and to the advertising and
promotional spaces within the ICQ Mail Service, the ICQ Mail Website and the ICQ
Client and has the sole authority to market and sell such advertising inventory;
provided that ICQ agrees that it will not include any advertisements or sell any
advertising inventory on the ICQ Mail Service or the ICQ Mail Website for or to
CP Competitors.  Further, ICQ shall be solely responsible for all obligations,
liabilities and duties under any and all agreements that ICQ has with third
parties and otherwise with regard to such advertisements.

6.2  Revenues from Premium Services.
     ------------------------------ 

     (a)  Revenue Sharing.  During the term of this Agreement, for any Core
          ---------------                                                  
Premium Services and Expanded Premium Services offered by CP which ICQ chooses
to offer to ICQ Mail Users, CP shall provide ICQ with its standard per user
wholesale price list for such services (the "Price List") and, subject to the
provisions of Section 6.2(b), ICQ shall pay CP for such premium services on a
per user basis at a rate per user which is the lesser of (i) the price listed on
the Price List less ****) or (ii) the **** price offered by **** service (or as
otherwise may be agreed to by the parties).  ****

     (b)  Volume Reductions.  All prices payable by ICQ to CP pursuant to 
          -----------------   
Section 6.2(a) for any Premium Service (****) shall be reduced in any quarter
by **** per each block of **** Active ICQ Mail Users using such Premium
Service during such quarter (but excluding the first such block of **** Active
ICQ Mail Users), up to a maximum reduction of **** from the prices payable
pursuant to Section 6.2(a). For example, if in Q1 the number of Active ICQ
Mail Users is **** then the prices otherwise payable during such quarter for
Core Premium Services or Expanded Premium Services would be reduced by ****
(i.e. **** for each full block of **** Active ICQ Mail Users, after the first
such block of **** Active ICQ Mail Users)

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           8
<PAGE>
 
6.3  No Other Revenue Sharing.  Except as expressly provided in this Section
     ------------------------                                               
6, ICQ shall be entitled to all revenues derived from, or related to, the
operation of the ICQ Service and the ICQ Mail Service, including without
limitation revenues from advertising and marketing and from the provision of
products and services, and, except as the parties may otherwise agree in
writing, shall not be required to share any portion of any such revenues with
CP.

6.4  **** represents **** that the **** to which **** hereunder are ****
Services or **** thereof ****.  For purposes of this Section 6.4, **** a web-
based email **** of **** (i.e. where **** is of ****) to customers with ****
(offered **** for which customers ****) that may ****.  Further, in the event
that during the term of this Agreement **** or any **** thereof pursuant to
which such **** terms provided **** that it shall also **** such ****.

6.5  Minimum Revenue Commitment.   ICQ agrees that in any month during the
     --------------------------                                           
term in which there are at least ****, CP shall be entitled to receive at least
the minimum amount of revenue calculated under this Section 6.5 (the "Minimum
Monthly Revenue").  The Minimum Monthly Revenue for any month shall be equal to
**** for each Active ICQ Mail User during such month ****, up to a maximum
amount of **** in ****.  By way of example of the foregoing, if during a
calendar month, there are ****, the Minimum Monthly Revenue for such month shall
be ****.  In connection with any quarterly report under Section 6.6, ICQ shall
calculate the Minimum Monthly Revenue for each month during such quarter.  If
the amount otherwise payable by ICQ during such quarter is less than the
cumulative Minimum Monthly Revenue for the months in such quarter, then ICQ
shall pay to CP the amount of such Minimum Monthly Revenue.  By way of example,
if during a quarter, the Minimum Monthly Revenue for the three (3) months is, in
the aggregate ****, and if the amount otherwise payable under this Section 6
(including payments under Sections 6.1 and 6.2) during such quarter would be
****, then ICQ shall pay CP **** with the quarterly report provided under
Section 6.6 (net of payments previously made during such quarter, if any).  If,
on the other hand, in the foregoing example, the amount otherwise payable under
this Section 6 (including any payments under Sections 6.1 and 6.2) during such
quarter, were ****, then ICQ shall pay such **** (net of any payments previously
made during such quarter, if any), and there shall be no additional amounts due
based on the Minimum Monthly Revenue.

6.6  Reports and Payments.  Within thirty (30) days following the end of each
     --------------------                                                    
calendar quarter, ICQ shall provide CP with a report that contains information
detailing the amount of any revenue payable to CP for such quarter pursuant to
the provisions of this Section 6.  Such report shall, with reasonable detail,
explain the basis upon which such revenue obligations have been determined and
be accompanied by payment in full of all amounts indicated on such report as due
for such month.

6.6  Audit Rights.  Each party shall have the right to have mutually
     ------------                                                   
acceptable independent CPA auditors (which auditors shall not be compensated on
a contingency basis and shall be bound to keep all information confidential
except as necessary to disclose discrepancies to the auditing party) audit and

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           9
<PAGE>
 
analyze the other party's relevant accounting records to ensure compliance with
the other party's payment obligations under this Section 6.  Any such audit
shall be permitted within thirty (30) days of receipt by the audited party of a
written request from the auditing party to audit, during normal business hours,
at a time mutually agreed upon; provided, however, that no audit of ICQ's
accounting records may be conducted during the months of June through September.
The cost of such an audit shall be borne by the auditing party unless a material
discrepancy is found, in which case the cost of the audit shall be borne by the
audited party.  A discrepancy shall be deemed material if it involves a payment
or adjustment of more than five percent (5%) of the amount actually due from the
audited party in any given quarterly period.  Neither party shall be audited
more frequently than annually.  Audits shall not interfere unreasonably with the
audited party's business activities and shall be conducted in the audited
party's facilities during normal business hours, at a time mutually agreed upon.
An audit may cover any period; provided that: (i) the period has not been
previously audited; and (ii) the period under audit is within a three year
period immediately preceding the commencement of the audit.  The audited party
shall promptly reimburse the auditing party for the amount of any discrepancy
arising out of such audit which indicates that the auditing party is owed
amounts hereunder as well as the costs of the audit, if applicable, as provided
above.

6.7  Penalty For Breach.  If CP fails to deliver any product or Update,
     ------------------                                                
including the initial version and any final Update after testing under Section
2.1(e), or otherwise fails to perform any material obligation hereunder within
the time frame required under this Agreement, or in the event the ICQ Mail
Service does not perform in accordance with requirements of Section 2.4 and
Exhibits B and C in any material way, then the following provisions shall apply:
(i) if any such delay or performance failure lasts for more than five (5) days
during any calendar month, then, for the entire such calendar month, the revenue
allocations under Section 6.1 and the prices payable by ICQ for Premium Services
will be reduced as follows: (i) if there was no reduction in the prior calendar
month, then CP's share of Net Advertising Revenues under Section 6.1 shall
decrease by **** (so that, if the share would otherwise be **** of the Net
Advertising Revenue for such month, it shall be **** of such revenues) and the
prices otherwise payable by ICQ under Section 6.2 shall be ****; and (ii) if
there was a reduction in the prior calendar month (i.e., there was a delay or
failure in such prior calendar month), then **** share of Net Advertising
Revenues **** shall **** of the **** (so that, if the share would otherwise be
**** of the Net Advertising Revenue for such month it shall be **** of such
revenues) and the prices otherwise payable by ICQ under Section 6.2 shall be
reduced by ****.  In any month that there is a reduction pursuant to this
Section 6.7, no Minimum Monthly Revenue shall be payable for such month.  By way
of example of the foregoing, if in three consecutive months, there are
reductions under this Section 6.7, then in the first such month the reductions
would be calculated under subpart (i) of the second preceding sentence and for
the next two such months (and any subsequent consecutive month), the reductions
would be calculated under subpart (ii) of the second preceding sentence.  In
calculating delays or failures hereunder there shall not be included any delay
or failure to the extent CP can demonstrate that it was caused by the failure or
delay of ICQ or AOL to perform any obligation hereunder.

7.   Stock Warrants

7.1  Warrants.  Attached hereto as Exhibit E is a form of Stock Warrant (the
     --------                                                               
"Warrant Form"), pursuant to which, in consideration of the execution of this
Agreement by ICQ, CP hereby concurrently grants to AOL: (a) warrants vested and
exercisable as of the date hereof entitling AOL to purchase 1,996,934 shares of
Series B Preferred stock of CP that CP represents shall, as of the date of this
Agreement, represent two percent (2%) of all equity interests in CP on a fully-
diluted basis (i.e., assuming exercise of all outstanding equity options and
full conversion of all notes, debts, loans and

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           10
<PAGE>
 
other instruments that are convertible into CP equity) (the "Vested Warrants");
(b) warrants entitling AOL to purchase up to an additional 3,993,867 shares of
Series B Preferred stock of CP that CP represents shall, as of the date of this
Agreement, represent an additional four percent (4%) of all equity interests in
CP on a fully-diluted basis (the "Additional Warrants").  The Additional
Warrants will vest and become exercisable in four (4) equal increments of one
percent (1%) of the outstanding equity each, upon registration of certain
numbers of ICQ Mail Service email boxes that are CP sub-branded as provided in
Section 3.2 (each "CP Sub-branded Boxes") within the first four (4) years of the
term of this Agreement (the "Vesting Period"), consisting of the Initial Term
and two Extension Periods, if exercised, as defined in Section 16.1(a) and (b),
respectively), as set forth more fully in the Warrant Form.

7.2.  Payment if Registration Milestones Not Met.  As noted above, and as set
      ------------------------------------------                             
forth in the Warrant Form, the Additional Warrants will vest in four (4)
increments upon registration within the Vesting Period of certain numbers of CP
Sub-branded Boxes.  If during the Vesting Period there are not registrations of
a sufficient number of CP Sub-branded Boxes to vest all of the Additional
Warrants (the "Minimum Vesting Registrations"), then ICQ shall pay to CP the sum
of **** (the "Additional Warrant Payment"), as additional consideration for the
issuance to it of the Vested Warrants and the Additional Warrants.  The
Additional Warrant Payment shall not be payable if ICQ terminates this Agreement
prior to the end of the Vesting Period pursuant to any right provided to ICQ
pursuant to Sections 16.1 through 16.5, but shall be payable if CP terminates
this Agreement for ICQ's breach as provided in Section 16.3 during the Vesting
Period and prior to achievement of the Minimum Vesting Registrations.  If the
Additional Warrant Payment becomes payable hereunder, it shall be paid within
thirty (30) days of the date it becomes payable (i.e., within thirty (30) days
of the end of the Vesting Period, or within thirty (30) days of any earlier
termination upon which the Additional Warrant Payment becomes payable).

7.3   Other Terms; Construction with Warrant Form.  All remaining terms of the
      -------------------------------------------                             
Vested Warrants and the Additional Warrants are set forth in the Warrant Form,
including without limitation, the exercise price, period and method of exercise
and the other rights preferences and privileges of AOL with respect to the
Vested Warrants and Additional Warrants. In the event of any conflict between
the provisions of this Section 7 and the provisions of the Warrant Form, the
provisions of the Warrant Form will control.   Attached to the Warrant Form as
Exhibit "A" is an Amended and Restated Investors' Rights Agreement, including a
Second Amendment thereto that will make AOL a party to that agreement.  CP will,
within thirty (30) days hereof, obtain all required signatures on the Second
Amendment to make it effective.

8.    Board Observation Seat Option

During the term of this Agreement, AOL shall have the right (but not the
obligation) to appoint one person to act as an observer to the board of
directors of CP, exercisable at AOL's option upon written notice to CP.  Such
observer will have the right to attend all meetings of CP's board of directors
and receive all notices thereof as if a member of the board, as well as to
receive all other notices sent to board members and all information reviewed or
available to board members, and will generally have all other rights of a board
member, other than the right to vote as a member of CP's board of directors.

9.    Exclusivity

Except as provided in this Section 9, the parties agree that the relationship
created by this Agreement shall be non-exclusive, and each of the parties may
enter into the same or a similar relationship with one or more third parties.
Without limiting the generality of the foregoing, ICQ shall be free to enter
into agreements with third parties for the use and integration of other web-
based email software and services

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           11
<PAGE>
 
with the ICQ Service, and CP shall be free to enter into agreements with third
parties pursuant to which it provides email products and services to such third
parties.  However, notwithstanding the foregoing, CP agrees that, during the
term of this Agreement, it shall not provide any email (or email related)
service or product to any company or entity that offers instant messaging or
similar or related online, real time messaging (an  "ICQ Competitor") nor shall
it integrate any offerings of an ICQ Competitor into any email service provided
by CP.  Further, CP agrees that it will not assist any of its customers or
partners in integrating an ICQ Competitor's instant messaging products or
services into any email product or service provided by CP or its affiliates,
unless such customer or partner insists upon such assistance after CP has used
commercially reasonably efforts to persuade such customer or partner to instead
use ICQ instant messaging products and services.  During the term of this
Agreement, CP will promote ICQ as CP's preferred integrated instant messaging
service and product.

10.    License from CP

10.1   License.
       ------- 

       (a)    Subject to all the terms and conditions of this Agreement, CP
hereby grants to ICQ and to AOL a worldwide, non-exclusive, non-transferable,
royalty-free license to use, reproduce, distribute directly and indirectly,
transmit and sublicense the client components of the ICQ Mail Software, if
any, in object code form only for use by end-users of the ICQ Mail Service
(including any Expanded Services).

       (b)    If **** the ICQ Mail Website (**** the ICQ Mail Service)
pursuant to ****, then, subject to all the terms and conditions of this
Agreement, **** in connection with such **** hereunder. Such **** may be in
**** both. If provided **** have the right to **** solely in connection with
**** (and applicable ****) in accordance with the terms and conditions of this
Agreement.

       (c)    The foregoing **** intended to **** to effectuate all of their
rights and conduct all of the business contemplated hereunder, including ****)
pursuant to the terms and conditions of this Agreement. **** (including ****)
in ****. The **** herein does not include, and **** shall have any right to
under any circumstances, or to **** (**** provided herein), **** or any
documentation that may be provided **** (other than as expressly provided
herein). In no event ****, except and only as reasonably necessary to ****
writing to abide by the terms of this Agreement ****. The **** shall
constitute Confidential Information of CP and subject to the restrictions of
Section 13. All copies of the

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           12
<PAGE>
 
ICQ Mail Software made hereunder shall include all proprietary notices included
on the copy provided by CP, and neither ICQ nor AOL may remove, deface or
obscure any of CP's or its licensors' proprietary rights notices on or in the
Software or on output generated by the Software; provided that the placement of
such notices shall be subject to ICQ's  prior written approval.  ICQ and AOL
agree that any and all copies of the ICQ Mail Software distributed to third
parties shall be pursuant to binding license agreements no less restrictive or
protective of CP's rights than this Section 10.1.  ICQ and AOL agrees that any
material violation of this Section 10.1 by ICQ or AOL shall constitute a
material breach of this Agreement.  CP agrees to provides the CP Email Software,
or portions thereof, with all required Documentation to ICQ and AOL as and when
needed for ICQ and AOL to exercise their rights this Agreement.  Promptly after
creation, CP will provide to ICQ and AOL, all Updates to the foregoing, together
with the ICQ Mail Software and all Updates thereto in object code form or, as
applicable, source code form. In addition, if ICQ transfers back to CP the
hosting responsibilities pursuant to Section 2.2(c), then ICQ shall return to
CP, or destroy, at CP's option, all hosting components of the ICQ Mail Software
(in both source and object code forms),and all copies thereof, in ICQ's or AOL's
possession or control.

     10.2  ****.  Subject to all the terms and conditions of this Agreement, and
effective only upon the Release Condition as defined herein, **** for the
purposes of undertaking any activity which **** as required hereunder.  ****
upon the occurrence of all of the following **** material obligations hereunder
to provide, maintain or support **** such material breach; **** such material
breach ****.  The foregoing does not include any right **** Confidential
Information of **** provided that **** the terms of this Agreement and provided
****.  Promptly after execution of this Agreement, and in any event within
thirty (30) days, **** acceptable to each party which shall be consistent with
the provisions of this Section.  The **** normal conditions requiring that ****
it has provided **** and that the **** to it.  **** (one that is a ****) if
****.  The **** upon **** that each ****  been met, unless****.  The **** shall
**** designed to make such agreement effective and binding despite any
subsequent bankruptcy of CP to the fullest extent permitted by law.  In
addition, **** any copies thereof, **** obtain such **** the terms of this
Section 10.2.

     10.3  Access to CP's Test Environment.  CP shall provide and make available
           -------------------------------                                      
to ICQ and/or AOL a test system that is a stable replication of the live system
for the testing of new features or customizations for a thirty (30) day period
prior to the planned release of such new features or

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           13
<PAGE>
 
customizations to the live system.  The primary (stable) test system shall meet
the same uptime requirements as the live system and provide the same processing
monitoring capability.  Once new features are released to the live system, the
primary test system will be updated to reflect the new features added to the
live system within a reasonable time period after such release to the live
system.

11.   Publicity

11.1  Press Releases.  After execution of this Agreement, CP and ICQ shall issue
      --------------                                                            
an initial joint press release, with terms to be mutually agreed by the parties,
regarding this Agreement and the relationship between the parties established
hereby.  The parties will mutually agree on the appropriate timing of such
release and any other initial public announcement of the relationship; provided
that such release and announcement will not occur until after February 15, 1999.
The initial press release and any other initial announcement  shall contain no
information regarding the financial or compensatory provisions of this
Agreement.  Following the initial press release, CP agrees that it shall not
issue any press release or make any public statement regarding ICQ or the ICQ
Mail Service, without the prior written consent of ICQ; provided, however, that
CP shall be permitted, without ICQ's prior consent, to merely list ICQ as one of
its industry partners.  Further, CP agrees to notify the following persons in
the event of any circumstances requiring public response:  (i) Jeanie Meyer at
RLM; and (ii) Pam McGraw and Ronald Grant at AOL.  AOL will provide contact
information for such parties.

11.2  Statements to Third Parties.  Neither party shall make, publish, or
      ---------------------------                                        
otherwise communicate, or cause to be made, published, or otherwise
communicated, any deleterious remarks whatsoever to any third parties concerning
the other party or its affiliates, directors, officers, employees or agents,
including without limitation, the other party's products, services, business
projects, business capabilities, performance of duties and services or financial
position.

12.   Ownership

12.1  ICQ Properties.  As between the parties, ICQ owns all copyrights, patents,
      --------------                                                            
trade secrets, trademarks and trade name rights and all other right, title and
interest in and to the ICQ Service, the ICQ Client, the ICQ Mail Service, the
ICQ Mail Website (including all URLs), the ICQ Branding Materials and the ICQ
Owned Customizations, and any Updates, enhancements and improvements thereto,
and all derivative works thereof and all proprietary rights therein, subject to
CP's ownership of the underlying software and technology as provided in Section
12.2.  Without limiting the generality of the foregoing, all right, title and
interest in all servers and server-based technology related to the ICQ Service,
including, without limitation, protocols, parameters, designs, specifications
and user identification algorithms and technology underlying such algorithms are
owned by ICQ.  CP agrees that it will not, at any time during or after this
Agreement, (i) do anything which may adversely affect the validity or
enforceability of any trademark, trade name, patent, copyright or trade secret
belonging to or licensed to ICQ (including any act, or assistance to any act,
which may infringe or lead to the infringement of any proprietary right in any
ICQ product or service), or (ii) exercise, or attempt to exercise, any
proprietary rights in any ICQ products or services, other than as expressly set
forth herein and in any other written agreement(s) that may be entered into by
the parties.

12.2  CP Properties.  As between the parties, CP owns all copyrights, patents,
      -------------                                                           
trade secrets, trademarks and trade name rights and all other right, title and
interest in and to the CP System, the CP Service, the CP Email Software and the
ICQ Mail Software (other than the ICQ Owned Customizations and ICQ provided
specifications), including, without limitation, all development tools, routines,
subroutines, applications, software and other materials that CP may use in
connection with branding the ICQ Mail Website or otherwise providing the ICQ
Mail Service (other than the ICQ Branding Materials and the


CONFIDENTIAL EXECUTION COPY           14
<PAGE>
 
URLs associated with the ICQ Mail Service, and the ICQ Owned Customizations and
ICQ provided specifications), and any Updates, enhancements and improvements
thereto, and derivative works thereof, and all proprietary rights therein,
subject to the license rights expressly granted to ICQ and AOL as set forth in
this Agreement.  Without limiting the generality of the foregoing, all right,
title and interest in all servers and server-based technology related to the CP
Service, including, without limitation, protocols, parameters, designs,
specifications and user identification algorithms and technology underlying such
algorithms are owned by CP.  ICQ agrees that it will not, at any time during or
after this Agreement, (i) do anything which may adversely affect the validity or
enforceability of any trademark, trade name, patent, copyright or trade secret
belonging to or licensed to CP (including any act, or assistance to any act,
which may infringe or lead to the infringement of any proprietary right in any
CP product or service), or (ii) exercise, or attempt to exercise, any
proprietary rights in any CP products or services, other than as expressly set
forth herein and in any other written agreement(s) that may be entered into by
the parties.

12.3  Co-Development.  Any intellectual property resulting from or constituting
      --------------                                                           
work product ("Work Product") from co-development efforts under this Agreement
shall be owned by ICQ, subject to CP's and ICQ's respective proprietary rights
in any underlying software or technology to the extent incorporated or included
in such Work Product.  ICQ and AOL hereby grant to CP a fully paid-up, royalty
free, perpetual, irrevocable and worldwide license to CP to use, reproduce,
distribute, transmit, sublicense,  modify and create derivative works of such
Work Product, and to make, use, offer for sale and sell products and services
that incorporate such Work Product or modifications thereof, provided that CP
shall not make, use, offer for sale or sell any products or services
incorporating such Work Product until nine (9) months after the termination or
expiration of this Agreement.  For purposes of this Agreement, "co-development"
shall consist of (a) work, even if performed solely by CP, that primarily
involves integration, pursuant to non-ICQ-provided specifications, of features
and functionality into the ICQ Service (or other real time messaging
technologies) or their functions and resources (such as member directories); and
(b) other work where employees of each party meet the statutory requirements
under U.S. patent and/or copyright law (such as 35 U.S.C. Sec. 16 and 17 U.S.C.
Secs. 101 and 201) to be deemed co-authors or co-inventors (including any work
product consisting of or conforming to published API's or specifications of ICQ
or AOL).  CP hereby assigns to ICQ or AOL, as appropriate, any and all of CP's
rights, title and interests in any co-developed work, and shall promptly deliver
to ICQ or AOL all such co-developed work, including without limitation source
code and all available Documentation, in form and manner specified by ICQ.  CP
shall cooperate with ICQ at ICQ's expense in documenting and perfecting all such
rights, including executing any necessary assignments, applications or other
documentation.  Notwithstanding any of the foregoing, this Section 12.3 shall
not construed to include, and CP retains sole ownership of all proprietary
rights in and to, features, functionality, and all other aspects of the CP
Service that prior to such development CP provides to other customers as part of
the CP Service or otherwise develops apart from this Agreement.  Further, this
Section 12.3 shall not be construed to include any generic modules (which shall
mean any software object, program, application, API, driver, tool, module, plug-
in, routine, subroutine, algorithm and/or other technology  that is not uniquely
specific to ICQ's or AOL's technical, operational or commercial requirements
under this Agreement and that can be readily adapted to other uses or
applications and that is not based on any ICQ or AOL proprietary specifications
             ---                                                               
or Confidential Information provided hereunder).

13.   Confidential Information.

Each party acknowledges that Confidential Information may be disclosed to the
other party during the course of this Agreement.  Each party agrees that, during
and after the term of this Agreement, it shall only use Confidential Information
of the other party as expressly permitted by this Agreement and shall take
reasonable steps, at least substantially equivalent to the steps it takes to
protect its own similar


CONFIDENTIAL EXECUTION COPY           15
<PAGE>
 
proprietary information, to prevent the duplication or disclosure of
Confidential Information, other than to its employees or agents who must have
access to the Confidential Information to perform such party's obligations
hereunder, who shall each agree to comply with this Section 13 or with similar
confidentiality obligations that are at least as protective of such Confidential
Information.

14.   Representations and Warranties

14.1  Joint.  Each party represents and warrants to the other party that: (i)
      -----                                                                  
such party has the full corporate right, power and authority to enter into this
Agreement, to grant the licenses granted hereunder and to perform the acts
required of it hereunder; (ii) the execution of this Agreement by such party,
and the performance by such party of its obligations and duties hereunder, do
not and shall not violate any agreement to which such party is a party or by
which it is otherwise bound; (iii) when executed and delivered by such party,
this Agreement shall constitute the legal, valid and binding obligation of such
party, enforceable against such party in accordance with its terms; and (iv)
such party acknowledges that the other party makes no representations,
warranties or agreements related to the subject matter hereof which are not
expressly provided for in this Agreement.

14.2  CP.  CP represents and warrants to ICQ that the ICQ Mail Service, 
      --   
including the ICQ Mail Software, and the CP System, do not and will not
infringe or violate any patents, copyrights, trade secrets, trademarks or
other proprietary rights of any third party. CP shall, at its sole cost and
expense, indemnify, defend and hold ICQ and AOL harmless from and against any
third party claim, loss, damage, expense or liability (including reasonable
attorney's fees and costs) that may result by reason of any breach of the
foregoing representation and warranty. The foregoing representation and
indemnity obligation shall not include any claim, loss, damage expense or
liability to the extent that it is based on or arises out of the ICQ Branding
Materials, ICQ provided specifications or other modifications to the CP
Service, the ICQ Mail Service or the CP System made in compliance with or
pursuant to ICQ's request, or the use of the ICQ Mail Service in combination
with the ICQ Service or any Expanded Service where such violation occurs only
as the result of such combination. ICQ shall promptly notify CP in writing of
any indemnifiable claim after ICQ first learns of such claim, and shall
provide CP with such assistance and cooperation as CP may reasonably request
from time to time in connection with the defense thereof. ICQ and AOL shall
have the right to employ separate counsel and to participate in the defense of
any such claim and to have their own respective counsel in attendance at all
times; ICQ and AOL will pay all costs of their counsel. Also, in its
discretion, ICQ or AOL may assume control of the defense of any infringement
claim; provided that under such circumstance ICQ or AOL shall bear all costs
of such defense (but not of any consequent judgment or liability or settlement
if made by AOL or ICQ without the prior written consent of CP which may not be
unreasonably withheld). If any settlement requires an affirmative obligation
of, results in any ongoing liability to, or prejudices or detrimentally
impacts in any way, ICQ or AOL, then such settlement shall require ICQ's
and/or AOL's written consent, as the case may be. If ICQ or AOL is enjoined or
restrained from exercising any of its rights under this Agreement as a result
of an infringement claim, CP shall, as promptly as practical either (i) obtain
a license at no cost to ICQ and AOL permitting continued use of the infringed
intellectual property rights on terms and conditions consistent with the
rights granted to ICQ and AOL hereunder, (ii) modify the software to perform
its intended function without infringing third party rights and without
materially adversely affecting the functionality or performance of the
software, or (iii) substitute software of comparable functionality and
performance. If CP is unable to obtain a license, modify the software to
perform its intended function without infringing third party rights, or
substitute software of comparable performance and instead chooses to simply
remove the infringing technology, CP shall be liable to ICQ and AOL for any
reasonable damages suffered by ICQ and AOL as the result of such removal,
including, without limitation, the cost to ICQ and/or AOL of replacing the
infringing technology, subject to ICQ's and AOL's duty to use reasonable
efforts to mitigate its damages. THE FOREGOING STATES ICQ'S AND


CONFIDENTIAL EXECUTION COPY           16
<PAGE>
 
AOL'S SOLE AND EXCLUSIVE REMEDY, AND CP'S SOLE AND EXCLUSIVE LIABILITY, WITH
RESPECT TO INFRINGEMENT.

15.   Limitations on Liability

15.1  EXCEPT AS EXPLICITLY PROVIDED HEREIN, NEITHER PARTY MAKES ANY WARRANTIES,
EXPRESS OR IMPLIED, REGARDING THE ICQ SERVICE, THE ICQ CLIENT, THE ICQ MAIL
SERVICE, THE ICQ MAIL WEBSITE, THE ICQ MAIL SOFTWARE, CP SYSTEM, THE CP SOFTWARE
OR OTHERWISE UNDER THIS AGREEMENT TO THE OTHER PARTY, AND EACH PARTY HEREBY
EXPRESSLY DISCLAIMS ALL SUCH WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE.

15.2  EXCEPT WITH RESPECT TO A BREACH BY CP OF ITS REPRESENTATION AND WARRANTY
UNDER SECTION 14.2, UNDER NO CIRCUMSTANCES SHALL EITHER PARTY BE LIABLE TO THE
OTHER PARTY FOR INDIRECT, INCIDENTAL, CONSEQUENTIAL, SPECIAL OR EXEMPLARY
DAMAGES (EVEN IF THAT PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES), WHETHER ARISING IN TORT (INCLUDING WITHOUT LIMITATION NEGLIGENCE),
CONTRACT, BY OPERATION OF LAW OR OTHERWISE, SUCH AS, BUT NOT LIMITED TO, LOSS OF
REVENUE OR ANTICIPATED PROFITS OR LOST BUSINESS.  DESPITE THE FOREGOING, IT IS
UNDERSTOOD THAT LOSS TO A PARTY OF PROFIT THROUGH NORMAL OPERATIONS AS
CONTEMPLATED BY THIS AGREEMENT THAT IT CAN DEMONSTRATE TO A COURT, ARBITRATOR OR
OTHER TRIER OF FACT IT WOULD MORE LIKELY THAN NOT HAVE RECEIVED IF THE OTHER
PARTY HAD NOT BREACHED THIS AGREEMENT WILL BE DEEMED DIRECT DAMAGES, NOT SUBJECT
TO THE LIMITATIONS OF THIS SECTION 15.2..

16.   Term and Termination.

16.1  Term.
      ---- 

      (a)   Initial Term.  Unless earlier terminated as set forth herein, the
            ------------                                                     
initial term of this Agreement (the "Initial Term") shall be two (2) years from
the Effective Date.

      (b)   Extension Periods.  Upon the expiration of the Initial Term, and 
            -----------------        
upon the expiration of the first, second and third Extension Periods, ICQ may
elect, in its sole discretion, to extend the term of this Agreement for an
additional one year period (each, an "Extension Period"), up to an aggregate
maximum of four (4) Extension Periods. ICQ shall be deemed to have exercised
its option for any Extension Period unless, at least thirty (30) days prior to
the expiration of the Initial Term, or of the first, second or third Extension
Periods, as applicable, ICQ provides written notice to CP that ICQ does not
wish to exercise its option for the forthcoming Extension Period.

16.2  Termination for Convenience.  ICQ may terminate this Agreement in its
      ---------------------------                                          
discretion at any time during the Initial Term or any Extension Period upon 90
days written notice to CP.

16.3  Termination for Breach.  Either party may terminate this Agreement at any
      ----------------------                                                   
time in the event of a material breach by the other party which remains uncured
after thirty (30) days written notice thereof.  In the event a party contests
the existence of a breach and/or termination of this Agreement, the other party
will continue to perform its obligations hereunder pending a final, non-
appealable judgement confirming the breach and termination, or an order of a
court of competent jurisdiction permitting such party to cease performing its
obligations hereunder.


CONFIDENTIAL EXECUTION COPY           17
<PAGE>
 
16.4  Termination Relating to Interactive Service.  ICQ may terminate this
      -------------------------------------------                         
Agreement, upon thirty (30) days' prior written notice to CP, if (a) CP enters
into an agreement pursuant to which a controlling interest in CP is to be
acquired by an Interactive Service or a person or entity owning a controlling
interest in an Interactive Service, (b) an Interactive Service or person or
entity controlling an Interactive Service actually acquires control of CP, (c)
CP enters into an agreement by which CP is to acquire a controlling interest in
an Interactive Service or a person or entity owning a controlling interest in an
Interactive Service, (d) CP actually acquires a controlling interest in an
Interactive Service or person or entity owning a controlling interest in an
Interactive Service, or (e) CP commences operating an Interactive Service either
directly or as a joint venture with another party or positions its business so
as to be substantially associated with an Interactive Service.  ICQ will not
have the right to terminate this Agreement under this Section 16.4 solely as the
result of any arrangement where CP directly or indirectly provides internet
access solely to permit users of the CP System to access and utilize their email
service.

16.5  Termination for Bankruptcy/Insolvency.  Either party may terminate this
      -------------------------------------                                  
Agreement immediately following written notice to the other party if the other
party (i) ceases to do business in the normal course, (ii) becomes or is
declared insolvent or bankrupt, (iii) is the subject of any proceeding related
to its liquidation or insolvency (whether voluntary or involuntary) which is not
dismissed within ninety (90) calendar days or (iv) makes an assignment for the
benefit of creditors.

16.6  Transition Assistance.  In the event of a termination of this Agreement
      ---------------------                                                  
pursuant to Sections 16.2, 16.3, 16.4 or 16.5, CP will provide to ICQ the
dedicated, full-time services of one (1) qualified engineer for a period of
ninety (90) days to assist ICQ and/or AOL in migrating or transitioning the ICQ
Mail Service to another provider.  In the event of termination for ICQ's breach
under Section 16.3, ICQ shall pay for CP's assistance in the migration or
transition at the then-current CP Time-and-Materials Rate and shall pay any out-
of-pocket expenses incurred by CP in connection with such migration or
transition.

16.7  Transition Period.  For a period of ninety (90) days following the
      -----------------                                                 
termination or expiration of this Agreement (the "Transition Period"), ICQ and
AOL shall have all of the rights granted hereunder and ICQ will have all of the
obligations with respect to the ICQ Mail Service created prior to the date of
termination or expiration (including all rights necessary to enable ICQ and AOL
to transition the ICQ Mail Service to another system without interruption of
service.  During such period, CP will not be entitled to any revenues or fees
hereunder if the termination is by ICQ pursuant to Sections 16.3 or 16.4; in any
other circumstance, CP will be entitled to the fees and revenue sharing for
services provided hereunder, subject to equitable reduction as the scope of
their services reduce hereunder.  Further, all end-user sublicenses of the ICQ
Mail Software shall survive the termination or expiration of this Agreement
pursuant to the terms of such end user license agreement as provided herein.
During the Transition Period, CP shall remain obligated to provide to ICQ the
support services described in Section 5.  Also, during the Transition Period, CP
shall provide ICQ with reasonable assistance in developing a new version of the
ICQ Client that is not integrated with (and does not contain) any portion of the
ICQ Mail Software and shall otherwise reasonably assist ICQ, as appropriate or
necessary, to migrate or transition the email services provided in connection
with the ICQ Service to another provider.  ICQ shall be entitled to seek
injunctive relief such as specific performance in the event CP fails to comply
with its transition obligations under Section 16.6 and this Section 16.7
(without resort to the dispute resolution mechanisms specified in Section 17).

16.8  Return of Information.  Upon the expiration or termination of this
      ---------------------                                             
Agreement, each party shall, upon the written request of the other party, return
or destroy (at the option of the party receiving the request) all Confidential
Information of the other party.


CONFIDENTIAL EXECUTION COPY           18
<PAGE>
 
16.9  Survival.  Notwithstanding anything to the contrary contained herein, the
      --------                                                                 
provisions of Sections 1, 4.2, 6.1, 6.2 and 6.5 (as to amounts accrued but
unpaid), 6.6, 7, 12, 13, 14, 15, 16.6, 16.7, 16.8, 16.9, 17 and 18 shall survive
the termination, cancellation or expiration of this Agreement.

17.   Dispute Resolution.
      -------------------

17.1  Management Committee.  The Parties will establish a "Management Committee"
      --------------------                                                      
made up of one (1) senior executive from each of the Parties for the purpose of
resolving Disputes (as defined below).

17.2  Dispute Resolution by Management Committee.  If the Parties are unable to
      ------------------------------------------                               
resolve any dispute by, controversy or claim arising under or related to this
Agreement or the transactions contemplated hereby (excluding any disputes
relating to intellectual property rights or confidentiality) (each a "Dispute"),
such Dispute will be promptly submitted for resolution by the Management
Committee.  The foregoing shall not limit the right of either party to at any
time apply to a court for an action for a temporary restraining order,
preliminary injunction or other equitable relief to stop or prevent irreparable
harm.

17.3  Binding Arbitration.  Except for the right of either party to apply to a
      -------------------                                                     
court for an action for a temporary restraining order, preliminary injunction,
specific performance or other equitable relief to stop or prevent irreparable
harm, all claims, disputes, controversies and other matters in question between
the parties to this Agreement, arising out of, or relating to this Agreement, or
the breach thereof, and which cannot be resolved by the parties pursuant to
Section 17.2, shall be settled only by binding arbitration in accordance with
the Commercial Rules of the American Arbitration Association ("AAA") then in
effect, including matters involving negligence, strict liability or intentional
acts or omissions by either party, provided that the following will apply:

      (a)   The parties shall have the right to discovery by any or all methods
provided in the Federal Rules of Civil Procedure.  The arbitrators may, upon
request, exclude any evidence not made available to the other party pursuant to
a proper discovery request from being used in the arbitration proceeding.

      (b)   Demand for arbitration shall be served upon the other party by
certified mail and specify in reasonable detail the nature of the dispute.  The
demand shall be effective upon receipt, shall be made within a reasonable time
after the claim, dispute or controversy has arisen, and shall in no event be
made more than one year after the claim or cause of action arises.  The
proceeding shall be held in Washington D.C.

      (c)   Within thirty (30) days after service of a demand for arbitration,
the parties shall attempt to agree upon a single arbitrator. If the parties
cannot agree upon a single arbitrator, either party may request the AAA to
appoint an arbitrator in accordance with its rules, subject to the
qualifications specified below. If the parties fail to agree on an arbitrator
from those named by the AAA or if for any reason the appointment cannot be
made from the AAA submitted lists, each party shall appoint an arbitrator
within seven (7) days thereafter and the third arbitrator shall be appointed
by the AAA. For any three member arbitration panel, the chairman shall be an
attorney with experience in handling disputes in the computer industry and the
other two shall have background or training in computer law, computer science
or the computer industry. A single arbitrator agreed upon by the parties shall
have a background or training in computer law, computer science or the
computer industry.

      (d)   The arbitrators shall have no power or authority to reform this
Agreement. The arbitrators shall have the power and authority to award
equitable relief other than reformation, including


CONFIDENTIAL EXECUTION COPY           19
<PAGE>
 
injunction and specific performance, nor to determine any matter requiring
agreement of the parties.  The arbitrators shall have no power or authority to
award punitive damages.  The arbitrators shall have the power and authority to
award consequential, special, indirect, or incidental damages only as permitted
by the terms of this Agreement.

      (e)   This Agreement shall remain in effect during the pendency of the
dispute resolution process without any interruption of service or performance by
either party.

      (b)   The cost of the arbitration shall be borne equally pending the
arbitrator's award. The prevailing party in any arbitration proceeding or
litigation hereunder shall be entitled, in addition to such other relief as
may be granted, to recover reasonable attorney's fees and the costs incurred
in connection with arbitration or litigation under this Agreement.

      (c)   The commencement, and any resolution reached as a result, of any
dispute resolution procedure under this Section shall be considered
confidential and shall not be disclosed by either party or by the arbitrators.

      (d)   The Federal Rules of Evidence will apply in toto to any such
Dispute.

      (e)   The decision of the arbitrator on the points in the Dispute will
be final and binding, and judgment on any award may be entered in any court
having jurisdiction thereof.

18.   General Provisions

18.1  Acknowledgment.  ICQ AND CP EACH ACKNOWLEDGE THAT THE PROVISIONS OF THIS
      --------------                                                          
AGREEMENT WERE NEGOTIATED TO REFLECT AN INFORMED, VOLUNTARY ALLOCATION BETWEEN
THEM OF ALL RISKS (BOTH KNOWN AND UNKNOWN) ASSOCIATED WITH THE TRANSACTIONS
CONTEMPLATED HEREUNDER.  THE LIMITATIONS AND DISCLAIMERS RELATED TO WARRANTIES
AND LIABILITY CONTAINED IN THIS AGREEMENT ARE INTENDED TO LIMIT THE
CIRCUMSTANCES AND EXTENT OF LIABILITY.  THE PROVISIONS OF THIS SECTION 18.1
SHALL BE ENFORCEABLE INDEPENDENT OF AND SEVERABLE FROM ANY OTHER ENFORCEABLE OR
UNENFORCEABLE PROVISION OF THIS AGREEMENT.

18.2  Independent Contractors.  The parties to this Agreement are independent
      -----------------------                                                
contractors.  Neither party is an agent, representative, or partner of the other
party.  Neither party shall have any right, power or authority to enter into any
agreement for or on behalf of, or incur any obligation or liability of, or to
otherwise bind, the other party.  This Agreement shall not be interpreted or
construed to create an association, agency, joint venture or partnership between
the parties or to impose any liability attributable to such a relationship upon
either party.

18.3  Notice.  Any notice, approval, request, authorization, direction or other
      ------                                                                   
communication under this Agreement will be given in writing and will be deemed
to have been delivered and given for all purposes (i) on the delivery date if
delivered by confirmed facsimile; (ii) on the delivery date if delivered
personally to the Party to whom the same is directed; (iii) one business day
after deposit with a commercial overnight carrier, with written verification of
receipt; or (iv) five business days after the mailing date, whether or not
actually received, if sent by U.S. mail, return receipt requested, postage and
charges prepaid, or any other means of rapid mail delivery for which a receipt
is available.


CONFIDENTIAL EXECUTION COPY           20
<PAGE>
 
      To ICQ:                           To CP:

      ICQ, Inc.                         Critical Path Inc.
      22000 AOL Way                     320 First Street
      Dulles, Virginia  20166           San Francisco, CA 94105
      Attention:  Fred Singer           Attention:   Mari Tangredi

      Phone:  (703) 265-2727            Phone:  (415) 808-8800

      Fax:  (703) 265-1204              Fax:  (415) 808-8777

      Copy to:

      America Online, Inc.
      22000 AOL Way
      Dulles, VA  20166
      Attention: General Counsel

      Fax:  (703) 265-2208


18.4   No Waiver.  The failure of either party to insist upon or enforce
       ---------
strict performance by the other party of any provision of this Agreement or to
exercise any right under this Agreement shall not be construed as a waiver or
relinquishment to any extent of such party's right to assert or rely upon any
such provision or right in that or any other instance; rather, the same shall
be and remain in full force and effect.

18.5   Entire Agreement.  This Agreement sets forth the entire agreement, and 
       ----------------
supersedes any and all prior agreements of the parties with respect to the
transactions set forth herein. Neither party shall be bound by, and each party
specifically objects to, any term, condition or other provision which is
different from or in addition to the provisions of this Agreement (whether or
not it would materially alter this Agreement) and which is proffered by the
other party in any correspondence or other document, unless the party to be
bound thereby specifically agrees to such provision in writing.

18.6   Amendment.  No change, amendment or modification of any provision of 
       ---------
this Agreement shall be valid unless set forth in a written instrument signed
by the party subject to enforcement of such amendment.

18.7   Further Assurances.  Each party shall take such action (including, but 
       ------------------
not limited to, the execution, acknowledgment and delivery of documents) as
may reasonably be requested by any other party for the implementation or
continuing performance of this Agreement.

18.8   Assignment.  Neither party may assign any of its rights, interest or
       ----------                                                          
benefits or delegate any of its duties under this Agreement, or otherwise
transfer this Agreement without the prior written consent of the other party;
provided that ICQ may assign this Agreement to any affiliate of ICQ (including
any entity controlling ICQ, controlled by ICQ or under common control with ICQ),
and provided further that either party may assign this Agreement for purposes of
reincorporation or change of domicile.  For purposes of the foregoing, any
merger of a party with or into, or sale of all or substantially all of the
assets of  a party to, or the acquisition of controlling interest in a party's
voting stock by, another entity shall be considered an assignment subject to the
foregoing restriction.  Subject to the foregoing, this


CONFIDENTIAL EXECUTION COPY           21
<PAGE>
 
Agreement shall be fully binding upon, inure to the benefit of and be
enforceable by the parties hereto and their respective successors and assigns.

18.9   Construction.  In the event that any provision of this Agreement
       ------------                                                    
conflicts with the law under which this Agreement is to be construed or if any
such provision is held invalid by a court with jurisdiction over the parties to
this Agreement, (i) such provision shall be deemed to be restated to reflect as
nearly as possible the original intentions of the parties in accordance with
applicable law, and (ii) the remaining terms, provisions, covenants and
restrictions of this Agreement shall remain in full force and effect.

18.10  Applicable Law; Jurisdiction.  This Agreement shall be interpreted,
       ----------------------------                                       
construed and enforced in all respects in accordance with the laws of the
Commonwealth of Virginia except for its conflicts of laws principles.  Each
party irrevocably consents to the exclusive jurisdiction of the courts of the
Commonwealth of Virginia and the federal courts situated in the Commonwealth of
Virginia, in connection with any action to enforce the provisions of this
Agreement, to recover damages or other relief for breach or default under this
Agreement, or otherwise arising under or by reason of this Agreement.  Each
party acknowledges that a violation of this Agreement could cause irreparable
harm to the other party for which monetary damages may be difficult to ascertain
or an inadequate remedy.  Each party therefore agrees that the other party shall
have the right, in addition to its other rights and remedies, to seek and obtain
injunctive relief for any violation of this Agreement.

18.11  Export Controls.  Both parties shall adhere to all applicable laws,
       ---------------                                                    
regulations and rules relating to the export of technical data and shall not
export or re-export any technical data, any products received from the other
party or the direct product of such technical data to any proscribed country
listed in such applicable laws, regulations and rules unless properly
authorized.

18.12  Headings.  The captions and headings used in this Agreement are inserted
       --------                                                                
for convenience only and shall not affect the meaning or interpretation of this
Agreement.

18.13  Counterparts.  This Agreement may be executed in counterparts, each of
       ------------                                                          
which shall be deemed an original and all of which together shall constitute one
and the same document.  This Agreement may also be signed by facsimile
transmission and any signature sent or received via facsimile transmission shall
constitute an original signature.

18.14  Force Majeure. CP shall not be responsible for any delays, errors,
       -------------                                                     
failures to perform, interruptions or disruptions in the ICQ Mail Services or
the CP System caused by or directly resulting from any acts of God, strikes,
lockouts, riots, acts of war, governmental regulations, fire, power failure,
earthquakes, severe weather, floods or other natural disaster or from any
unforeseeable events outside of CP's reasonable control occurring with respect
to ICQ, ICQ Mail User's or any third party's hardware, software or
communications equipment or facilities (not including any subcontractor of
services provided by CP hereunder) (each, a "Force Majeure Event").  The
foregoing shall not relieve CP from


CONFIDENTIAL EXECUTION COPY           22
<PAGE>
 
responsibility to the extent that reasonable actions or actions normally
provided in the industry or required as a result of the obligations of CP under
Exhibits B or C (such as back-up servers, alternative routing providers, etc,)
would have made such events within CP's reasonable control or prevented any such
delay, error, failure, interruptions or disruptions.  In addition, in no event
will a Force Majeure Event permit any delay, error, failure, interruption or
disruption for longer than a commercially reasonable time considering the event
and after such reasonable time period, the Force Majeure Event shall not longer
be deemed to exist or apply.  If the Force Majeure Event lasts for a period of
sixty (60) days or longer, then ICQ shall be entitled to terminate this
Agreement upon written notice to CP.  Neither party shall have any liability or
obligation to the other party as a result of such termination, and CP agrees to
provide reasonable transition assistance pursuant to Section 16.7 if not
prevented by the Force Majeure Event.

18.15  Insurance.  CP, at its cost and expense, shall secure and maintain
       ---------                                                         
adequate insurance coverage as is necessary, as a reasonable prudent business
matter, for CP to bear all of its obligations under this Agreement.  Maintenance
of such insurance shall not be deemed to relieve or limit CP of any
responsibility or obligation hereunder whatsoever.  CP assumes full and complete
liability for all injuries to, or death of, any person or for any damages to
property arising from its acts or omissions.  CP will add ICQ and AOL as
additional insureds on all appropriate insurance policies, including all
liability policies, with endorsements that require 30 days notice of ICQ and AOL
of any cancellation of such policies, and shall promptly provide ICQ and AOL
with copies of such policies and endorsements and any changes thereto from time
to time.  CP's insurance shall be primary as to any other insurance the ICQ or
AOL may have.

IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the
date first above written.

ICQ, INC.                                 CRITICAL PATH INC.


By: _______________________________       By: _______________________________

Print Name:  ______________________       Print Name:  ________________________

Title: ____________________________       Title: ______________________________



CONFIDENTIAL EXECUTION COPY           23
<PAGE>
 
                                  EXHIBIT A

                                 Definitions

"AOL" shall mean America Online, Inc., a Delaware corporation.

"Active ICQ Mail User" shall mean, for any given period (i.e., a calendar
quarter for measurements specified herein as applying for a calendar quarter or
for a calendar month for periods specified herein as applying for a calendar
month) an ICQ Mail User who, during such applicable period accesses his email
account on the ICQ Mail Service at least once (whether or not such ICQ Mail User
actually sends or receives email from such account during such period).

"Change of Control" shall mean any event that results in any person or entity
not having control of a referenced party as of the date hereof acquiring control
of such party by any means whatsoever, including (i) the consummation of a
reorganization, merger or consolidation or sale or other disposition of
substantially all of the assets of the referenced party; or (ii) the acquisition
by any individual, entity or group (within the meaning of Section 13(d)(3) or
14(d)(2) of the Securities Exchange Act of 1933, as amended) of either
beneficial ownership (within the meaning of Rule 13d-3 promulgated under such
Act) of  a sufficient percentage of the voting securities or right to vote or
take action as to result in control or the contractual right to exercise control
In all instances, the acquisition of more than 50% of either (A) the then
outstanding shares of common stock or other common equity of such party; or (B)
the combined voting power of the then outstanding voting securities of such
party entitled to vote generally, including as to the election of directors or
other governing body shall conclusively be deemed control.

"Control" (including the terms "controlling", "controlled by" or "under common
control with") shall mean the possession, direct or indirect, of the power to
direct or cause the direction of the management and policies of a person,
whether through the ownership of voting securities, by contract or otherwise.

"Confidential Information" shall mean any information relating to or disclosed
in the course of the negotiation or performance of this Agreement, which is, or
should be reasonably understood to be, confidential or proprietary to the
disclosing party, including, but not limited to, the existence and material
terms of this Agreement, User Information or other information about ICQ Users,
technical processes and formulas, source codes, product designs, sales, cost and
other unpublished financial information, product and business plans, projections
and marketing data.  Without limiting the generality of the foregoing, all
protocols, parameters, designs, specifications and user identification
algorithms relating to the ICQ Service are Confidential Information of ICQ.
"Confidential Information" shall not include information that the receiving
party can establish is (a) already lawfully known to or independently developed
by the receiving party, (b) generally known to the public, (c) lawfully obtained
from any third party, (d) required to be disclosed by law, or (e) permitted to
be disclosed pursuant to the terms of this Agreement.

"Core Premium Services" shall mean the following services in the form currently
offered by CP or as specified as Premium Services to be available at launch on
Exhibit B: expanded mail box, integration with client email, mail forwarding,
email to voice service, POP access, and opt-in mail services, together with all
Updates that merely fix errors or bugs.  From time to time during the term of
this Agreement, the parties may, by mutual agreement, designate additional CP
services as "Core Premium Services" or may remove certain CP services from the
definition of "Core Premium Services."

"CP Competitors" shall mean solely entities whose primary business is to provide
web-based email services which are directly competitive with the CP System.  CP
Competitors will not include any entity that only provides web-based email
services as part of a general Interactive Service.

"CP Email Software" shall mean the current standard suite of client and host
software products distributed by CP that enables the provision of email and
related communication services to end users through one or more Internet
websites, all Documentation therefor and any Updates thereto.


CONFIDENTIAL EXECUTION COPY           24
<PAGE>
 
"CP Service" shall mean the system and services pursuant to which CP provides
web-based email, including without limitation the CP Email Software and the
hosting and other services required in connection therewith.

"CP System" shall mean the software and related systems pursuant to which CP
provides the CP Service, including without limiting the CP Email Software and
all intellectual property rights therein.

"CP Time-and-Materials Rate" shall mean the rate of $200 per hour for the first
one-year period during the term of this Agreement, and for each year thereafter,
a rate that is an increase from the rate for the previous year that is no more
than  the lesser of the increase in the Consumer Price Index for All Consumers
(Washington D.C. area) and 5%.

"Documentation" means all documentation at any times existing relating to
applicable software, including all technical documentation and source code
notations used or created by the creating party or provided to or used by any
end-user or any support or other technical personnel.

"Expanded Premium Services" shall mean any Premium Email Services that may be
offered by ICQ, CP or any third party from time to time, including any Updates
to the Core Premium Services other than Updates that are bug fixes or correct
errors but specifically excluding Core Premium Services as they exist as of the
date hereof and any Updates that merely fix bugs or correct errors.

"ICQ Client" shall mean the client software developed and distributed by ICQ
that enables ICQ Users to access and use the ICQ Service, and any Updates
thereto.

"ICQ Mail Service" shall mean the web-based email and email-related services
provided to ICQ Mail Users by ICQ, utilizing the services of CP hereunder,
including any Updates thereto.

"ICQ Mail Software" shall mean the customized version(s) of the CP Email
Software created by CP pursuant to the provisions of Section 2.1, including both
client components intended to run on an end-user's computer and host components
used to provide and operate email services through the ICQ Mail Website and
including all Documentation therefor and all Updates thereto.

"ICQ Mail User" shall mean an ICQ User who, pursuant to the provisions of
Section 4.1, has registered with ICQ to use the ICQ Mail Service.

"ICQ Mail Website" shall mean have the meaning given to such term in Section
2.2(a).

"ICQ Service" shall mean the ICQ-branded service, currently available through
the Internet, that enables ICQ Users to communicate with one another, including
through real-time, personal text messaging, and to monitor each other's online
status.

"ICQ User" shall mean any registered user of the ICQ Service and any registered
user of the ICQ Mail Service (including any Expanded Service). As set forth on
Exhibit B, it is understood that, in Phase II (as described on Exhibit B), the
ICQ Mail Service will be offered to the general public, including those who are
not registered users of the ICQ Service.

"Interactive Service" shall mean an entity offering one or more of the
following: (i) online or Internet connectivity services (e.g., an Internet
service provider); (ii) an interactive site or service featuring a broad
selection of aggregated third party interactive content (or navigation thereto)
(e.g., an online service or search and directory service) and/or marketing a
broad selection of products and/or services across numerous interactive commerce
categories (e.g., an online mall or other leading online commerce site); and
(iii) communications software capable of serving as the principal means through
which a user creates, sends and receives real time online messages.


CONFIDENTIAL EXECUTION COPY           25
<PAGE>
 
"Premium Email Services" shall mean any existing or future products or services
that are ancillary or complementary to the provision of typical, standard email
services, including those for which end-users are generally charged an
additional or separate fee.

"Severity 1 Problems" are problems that in ICQ's reasonable determination halt
or materially disrupt product execution, cause a major loss of product
functionality or reduction in capability of core functions or data corruption or
damage or create an emergency  which will cause significant financial or
reputation loss or other loss or business disruption.

"Severity 2 Problems" are problems that in ICQ's reasonable determination are
not Severity 1 Problems but that require prompt correction but do not prevent
the material use of the core functions of the system (such as, for example, an
isolated, consistently reproducible problem resulting in system crash loss of
core or material functionality, but which can be avoided without undue
disruption or the failure of a significant utility).

"Severity 3 Problems" are problems, including all other bugs, that in ICQ'
reasonable determination are not Severity 1 Problems or Severity 2 Problems.

"Standard Email Services" shall mean all email services and functions included
in the Specifications (including Phase II specifications), other than those
expressly listed as Premium Services, together with such other email services as
from time to time become considered typical, standard email services or for
which no fee is generally charged by other web-based email services or otherwise
agreed to by the parties.

"Updates" shall mean, as to any product, all subsequent releases thereof
including maintenance releases and services patches, error corrections,
upgrades, upgrades, enhancements, additions, improvements, extensions,
modifications and new, replacement or successor versions or products, and all
related Documentation.


CONFIDENTIAL EXECUTION COPY           26
<PAGE>
 
                                  Exhibit B

                 Initial Specifications for ICQ Mail Service

                       (Developed and Provided by ICQ)

--------------------------------------------------------------------------------
                                    ****

                                   Draft 2.0
--------------------------------------------------------------------------------


                                        

I.      Objectives
II.     Timeframe and Delivery
III.    ICQ Deliverables
IV.     Phase I Features
V.      Phase II Features


1.2  I.  ICQ Email Objectives:


****


II.  Timeframe and Delivery

****

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           27
<PAGE>
 
****

III  ICQ Deliverables

****

IV  Phase I Features

****


*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           28
<PAGE>
 
****


1.4  International Languages:


At launch, ICQ Email will support email in the following 7 languages (including
interface and spell checking tools):

 . French

 .  German

 .  Spanish

 .  English

 .  Swedish

 .  Portuguese

 .  Dutch


1.5  Functional Requirements:


 . Basic Email Functions

Like most email services, ICQ Email will support:

     .   Sending of mail
     .   Reading of mail
     .   Reply
     .   Reply to all
     .   Attach file
     .   Folders
     .   Address book (see ICQ Integration below)

     *   CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN
     INFORMATION CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT
     CONFIDENTIAL PORTIONS HAVE BEEN OMITTED FROM THE PUBLIC FILING AND HAVE
     BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           29
<PAGE>
 
     .   Multi-language spell checking (see International Languages above)

     .   Custom filtering (see below)

     .   User customized signature files (see below)


  The inbox screen will have the capability to list all email received by a
  master account, sub accounts, or external POP accounts that have been
  configured by the user, including a field indicating the recipient address
  (refer to mockup).


  ****


 .  Custom Filtering

In addition to the basic spam filtering of objectionable domains (from a
frequently updated Spammer master list provided by vendor), members will be able
set certain customized rules for the handling of different emails.  Incoming
messages can be discriminated on the basis of address of sender, domain of
sender (handled by "sender", "contains", "domain.com"), or address of recipient.


 .  Forwarding

The mail service will have the ability to automatically forward mail from one
account to any target email address.  The conditions and target of the forward
can be set either in preferences (when a member is going on vacation).
Forwarding will be offered as a premium service.


 .  Programmed Signature Files


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CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           30
<PAGE>
 
Members will be able to tailor their signature files to whatever they want,
including hyperlinked different signatures for different sub-accounts.  Beneath
the member signature file, ICQ will append a system signature file.  This ICQ
signature will support URLs, and be programmable according by domain, including
vanity domains.


 .  Outbound Mail Limits

ICQ will be able to limit, on a domain basis, the maximum number of recipients
addressed on outbound mail.  The limit will be configurable by domain at least
between 10 and 100, with a default setting for new domains of 20.



****


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CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           31
<PAGE>
 
****


V  Phase II Features


****

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CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           32
<PAGE>
 
  ****

  *  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN
  INFORMATION CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL
  PORTIONS HAVE BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED
  SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           33
<PAGE>
 
****

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           34
<PAGE>
 
****

*  CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONTAINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           35
<PAGE>
 
                                  Exhibit C

                CP Hosting and Email Performance Obligations

 Any content or any other data from non-CP hosted servers shall not be included
 in the calculation or measurement of the performance metrics and all other CP
                          requirements of this Exhibit


<TABLE>
<CAPTION>
Key Process/Measurement          Accuracy/functionality Standard                        Timeliness Standard 
<S>                          <C>                                            <C>
-----------------------------------------------------------------------------------------------------------------
 
Service Availability         Min acceptable: ****% average weekly           Schedule downtime to occur only on 
                             availability (24 hrs, Saturdays, 7             Saturdays, 12 am - 3 am **** Pacific
                             days a week, 365 days) excluding               time no more than 26 times per    
                             planned maintenance windows.                   year or with written permission 
                             Users should see screen explaining             from ICQ. In addition, planned system 
                             downtime or warning of potential               downtime should be communicated to 
                             lag time in messages                           ICQ at least 48 hours in advance and     
                                                                            should not occur at peak traffic 
                                                                            times 
-----------------------------------------------------------------------------------------------------------------
 
Processing emails            **** of all messages processed by              Monthly avg response time for http
                                                                            sessions under **** for **** of
                                                                            user's service requests
                             the Service will be handled without            End to end time to send/receive 
                                                                            a message
                             Error meaning that                             from another service should be
                             the message is intact                          less than **** for **** of all
                             upon receipt.                                  messages. However, CP will not 
                                                                            be responsible for delays      
                                                                            outside of the CP System or    
                                                                            other Force Majeure Events      

                                                                            End to end time to send/receive a 
                                                                            message that is hosted internally 
                                                                            by CP should be less than **** for 
                                                                            **** of all messages. 

---------------------------------------------------------------------------------------------------------------
</TABLE>
* CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONATINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           36
<PAGE>
 
<TABLE>
<CAPTION>
<S>                                     <C>                                          <C>  
Service response time                   Images load, links work **** of time         All pages should completely load
                                                                                     (including images) and functions
                                                                                     completed in a time equal or less
                                                                                     than other leading webmail service providers

Capacity/Planning                       Peak usage for all components /              Thresholds to generate a new
                                        **** capacity.                               Capacity upgrade should be initiated
                                                                                     at **** utilization for all components   

                                        AOL agrees to provide estimated 
                                        quarterly projections to CP of
                                        anticipated new mailboxes
                                        to assist in such capacity
                                        planning.
---------------------------------------------------------------------------------------------------------------------------------  
 
Customer service                        Support all end user problems/issues         **** of emails acknowledged
                                        that have been forwarded from ICQ's 
                                        Customer Service 

inbound/outbound emails                 with Service including but not               Within **** or within **** with auto-  
                                        limited to                                   responders; **** of emails

                                        Premium Services, but not including          responded to within **** business days
                                        Non-affiliated Premium      

                                        Services (such as JFAX). Minimum             and **** of problems will have 
                                        acceptable ****                              resolution within

                                        accurate; Minimum coverage of                **** business days  
                                        emails                                       

                                        7 am - 5 pm Pacific Standard Time
                                        plus part-time coverage in 
                                        evenings and weekends to support
                                        performance standards.
---------------------------------------------------------------------------------------------------------------------------------
 
Testing                                 CP to conduct ongoing system testing         Testing should be continuous (in 
                                        to                                           

                                        ensure that **** of performance              intervals less than or equal to ****

                                        metrics are tracked; Should include          ****): **** of problems with

                                        but not limited to continuous page           any of the performance metrics including
</TABLE>

* CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONATINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.

CONFIDENTIAL EXECUTION COPY           37
<PAGE>
 
<TABLE>
<S>                                     <C>                                            <C>   
                                        loading testing of a ICQ URLS                  but not limited to those listed in 
                                        from multiple geographically separate          Exhibit E, must be identified within a 
                                        monitoring locations on the internet and       **** hour period and plan of resolution 
                                        as well as testing of as well as testing       ready within **** hours of 
                                        of email/all other service                     problem identification/notification
                                        throughput times (send, receive, forward
                                        etc) from at least one external source

                                        "Performance metrics" means the 
                                        service availability, processing emails 
                                        and service response time requirements
                                        indicated above.

                                        CP will monitor and take a baseline for
                                        the first 30 days of service and track
                                        degradation on an ongoing basis.
---------------------------------------------------------------------------------------------------------------------------------
 
Monthly Reporting                       **** accurate                                  Reports should be received no later than 5
(For each ICQ email domain,             Monthly reports to include:                    business days after close of month
including "vanity domains"              CP System uptime                            
and for all premium                     Number of new user mailboxes             
services individually)                  Number of deleted user mailboxes
                                        Total number of user mailboxes

                                        Member storage used for user
                                        mailboxes- (to be available for Phase 2)

                                        Number of CP System Outages

                                        System total downtime and average

                                        daily and monthly downtime
 
                                        Changes to CP System
                                        Reason for change
                                        Areas affected
</TABLE>

* CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONATINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           38
<PAGE>
 
<TABLE>
<CAPTION>
<S>                                     <C>                                            <C>     
Daily Reporting as available            Number of messages received                    Daily reports should be 
                                                                                       available every 24

(For each ICQ email domain,             Number of recipients                           hour period on a password-accessible

including "vanity domains"              Number of messages sent                        website
                                        
and for all premium                     Number of senders 
                                           
services individually)
---------------------------------------------------------------------------------------------------------------------------------
 
System Outage Reports                   Specific System outage details                 Reports should be faxed within **** of

                                        Time of Outage                                 outage
                                           
                                        Length of outage

                                        Affected areas

                                        Reason for outage
 
                                        ICQ contact notified (if any) and
                                        time of notification

                                        Remedy to prevent outage
                                        reoccurrence
---------------------------------------------------------------------------------------------------------------------------------
 
System Outage Response                  If a system outage occurs, CP will             System outages will be identified 
                                                                                       within ****   

                                        report outage to ICQ upon discovery            **** of occurrence, and ICQ will be
                                        
                                        First, by phone call to ICQ NOC if any         contacted within same time frame.
                                        
                                        Next, by email to designated address  
                                        which

                                        ICQ will provide

                                        Further, CP will make available a
                                        support

                                        pager number manned 24/7/365.
---------------------------------------------------------------------------------------------------------------------------------
Data Integrity                         User must be able to access all                 To extent measurable, will match or
                                        
</TABLE>

* CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONATINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.

 
CONFIDENTIAL EXECUTION COPY           39 
<PAGE>
 
<TABLE>
<CAPTION>
<S>                                     <C>                                            <C>     
                                        mailbox and folders contents and               exceed Other Leading Webmail Service 
                                                                                       Providers; **** of such 
                                                                                            
                                        preferences **** of time (subject to           unaccessed data should be restored within 

                                        mutual agreement on archiving and              competitive standards to be mutually

                                        offline storage policy for older               agreed upon
                                           
                                        information)
---------------------------------------------------------------------------------------------------------------------------------
 
Security                                Security features and system                   If leading competitor(s) 
                                        
                                        capabilities should be equal or better         offers a new security element,
                                        
                                        to that offered by Other Leading               Critical Path will match it within a 
                                        Webmail Service Providers                      reasonable time period 
                                                                                  
                                        consistent with 
                                        
                                        product spec and timeline
---------------------------------------------------------------------------------------------------------------------------------
 
Spam Controls                           Spam control features and system               If a leading competitor offers a new spam 
                                                                                            
                                        capabilities should be equal or better         control element, Critical Path should 
                                                                                  
                                        to that offered by Other Leading               Match it with a reasonable time period. 
                                        Webmail Service Providers                      Such tools will be
                                                                                     
                                        and consistent with standards                  continuously running and account can be
                                        established

                                        throughout the ICQ web-site                    closed, if necessary, immediately after
                                                                                       reasonable investigation is conducted

                                        Critical Path will offer identification 
                                        statistics

                                        and controls to continuously monitor for

                                        outbound spam of any kind and

                                        allow for shutting down account
---------------------------------------------------------------------------------------------------------
</TABLE>

* CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONATINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           40
<PAGE>
 
                                   Exhibit D

                        CP Back-End Support Obligations


Available Contacts; Response
----------------------------

CP shall appoint dedicated technical contacts with reasonable and substantial
relevant training and experience to whom ICQ may address all technical questions
relating to the ICQ Mail Software.  Such contacts must be available twenty four
hours a day, 7 days a week, 365 days a year.

Such contacts will be available by phone or pager 24 hours a day.  Calls not
answered should be returned in all instances within one-half hour.

Additional Technical Support.
---------------------------- 

At ICQ's request, CP will provide to ICQ appropriate technical personnel to
provide support and advice to ICQ at locations specified by ICQ at the then
current CP Time-and-Materials Rate or as otherwise agreed.  Actual travel
expenses shall be reimbursed to CP under ICQ's standard practices and policies,
including maximum amounts for reimbursement and coach air travel.

Error Correction
----------------

CP shall correct problems as specified herein:

 .   For Severity 1 Problems, CP will respond within **** and use best commercial
    efforts to provide ICQ a patch, workaround, or other temporary solution
    within **** after ICQ notifies CP and a permanent problem resolution within
    **** calendar days

 .   For Severity 2 Problems, CP will respond with **** and use best commercial
    efforts to provide ICQ a patch, workaround, or other temporary solution
    within **** hours after ICQ notifies ICQ and a permanent problem resolution
    within ****

 .   For Severity 3 problems, CP will use best commercial efforts to provide a
    patch, work around or other temporary solution within **** after ICQ
    notifies ICQ and a permanent problem resolution must be provided within a
    time frame that is commercially reasonable considering the severity of the
    problem and in no event later than the next scheduled release (or earlier if
    mutually agreed).

If any problem cannot be reproduced by CP after best commercial and prompt
efforts, CP and ICQ shall mutually determine how to reproduce the problem and
correct it.

Training
--------

CP will, at no cost to ICQ, provide ICQ personnel with sufficient training to
enable ICQ to undertake its obligations and obtain its benefits hereunder.  The
parties will mutually agree on the amount and content of such training, the
personnel who will be trained, the timing of such training and location of such
training.  Each party will pay its own travel expenses for such training.

* CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO CERTAIN INFORMATION
CONATINED IN THIS EXHIBIT.  THROUGHOUT THIS EXHIBIT CONFIDENTIAL PORTIONS HAVE
BEEN OMITTED FROM THE PUBLIC FILING AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION.


CONFIDENTIAL EXECUTION COPY           41
<PAGE>
 
Spamming Response
-----------------

CP shall promptly respond and resolve any spam issues on the ICQ Mail Service,
including but not limited to using commercially reasonable efforts to block spam
(which efforts will be not be less than those required under Exhibits B and C.)




CONFIDENTIAL EXECUTION COPY           42
<PAGE>
 
                                   Exhibit E

                              Stock Warrant Form




CONFIDENTIAL EXECUTION COPY           43
<PAGE>
 
                                   EXHIBIT F

                    ACCEPTABLE USE POLICY AND TERMS OF USE

        [THIS POLICY IS ONLY FOR REFERENCE IN THE EVENT OF A CLAIM FOR 
                      INDEMNIFICATION UNDER SECTION 4.2]

                             Acceptable Use Policy

     This Acceptable Use Policy ("AUP") provides a set of guidelines that
Customers and End Users of the services provided by Critical Path Inc.
("Services") must follow in the use of their Services accounts.  Critical Path
reserves the right to update this AUP often.  Please review this AUP on a
frequent basis to stay current on the acceptable uses of the Services.

Prohibited Activities

     . Customers and End Users may not transmit or disseminate:  (i)
advertising, chain letters, spam, junk mail or any other type of unsolicited e-
mailing (whether commercial or informational) to persons or entities that have
not agreed to be part of such mailings; (ii) harassing, libelous, abusive,
threatening, obscene or otherwise objectionable materials or materials which
infringe or violate any third party's copyright, trademark, trade secret,
privacy or other proprietary or property right, or that could constitute a
criminal offense, give rise to civil liability or otherwise violate any
applicable law or regulation; or (iii) viruses or other harmful, disruptive or
destructive files.

     . In addition, Customers and End Users may not use or attempt to use
another person's or entity's account, service or system without authorization
from the owner, nor will any Customer or any End User interfere with the
security of, or otherwise abuse, the Service, system resources or accounts, or
any network or another user's use or enjoyment of the mail services.

     . No Customer or End User may forge header or address information.

     Following are more specific (but not exhaustive) examples of the prohibited
activities and Critical Path's policies with respect to them.

Unsolicited Bulk E-mail (popularly known as "spam")

Without exception, Critical Path does not tolerate the practice of mass-mailing
unwanted email solicitations of any type, regardless of content, and will not
permit its Customers or End Users to transmit or disseminate this type of email
using the Services.

     . Any Customer or End User who sends unsolicited advertisements or
solicitations, commercial or otherwise, may have its account disabled and be
disallowed further service.

     . Each Customer is responsible for ensuring that the Services are used in
an appropriate manner by Customer's End Users. Therefore, the Customer must take
steps to manage the use of the Services so that violations of this AUP and other
network abuse is minimized. The Customer must also make contact information
available to its End Users, respond in a timely manner to any complaints and, if
applicable to Critical Path's Services, forward such complaints to Critical Path
for consideration.

 . In extreme cases, Critical Path may immediately suspend the use of any account
in order to prevent further abuse or damage to e-mail systems or otherwise
protect Critical Path's interests.  If this occurs, Critical Path will notify
the Customer as soon as possible.


CONFIDENTIAL EXECUTION COPY           44
<PAGE>
 
     . Unsolicited advertisements or solicitations sent from other networks
which reference e-mail accounts hosted by Critical Path will be treated as if
they originated from the referenced account, unless Critical Path knows, or has
sufficient evidence to believe, that the message originated with some unrelated
party.

 . Likewise, postings made to usenet newsgroups or other online forums which
reference e-mail accounts hosted by Critical Path, and are deemed to be
inappropriate according to this AUP, the forum's ethical standards or other
general Internet use standards, may be treated in the same manner as unsolicited
bulk e-mail above.

Filtering of Incoming E-mail

 . It is Critical Path's policy to respect the privacy of its Customers and their
End Users.  Critical Path does not censor or control the contents of Customers'
and End Users' e-mail messages.  Customers and End Users are responsible for the
contents of the messages obtained through the Services, and the consequences of
any such messages.

 . As owner of the equipment and other resources used in providing the Services,
Critical Path reserves the right to employ blocking or filtering software or
other monitoring devices or techniques if deemed necessary or reasonable to
detect and/or protect spam with respect to electronic communications received by
Customers or End Users from other entities.

     . Whenever possible, Critical Path will attempt to notify the party being
blocked before such action occurs.

Illegal Activities

 . The Services offered may only be used for lawful purposes.  Transmission,
distribution, or storage of any information, data or material in violation of
any applicable law, regulation, ordinance or other rule imposed by any
governmental authority, is prohibited. This includes, but is not limited to,
material protected by copyright, trademark, trade secret, or other proprietary
right.

 . Critical Path will cooperate with law enforcement and other legal authorities
in investigating claims of illegal activity.

     . Critical Path will not release any personally-identifiable information
regarding its Customers (other than information that is already publicly
available, such as the InterNIC's WHOIS database) or their End Users to any
third party except to the extent necessary or appropriate to cooperate with such
law enforcement or other legal authorities, to comply with applicable laws or
regulations or in legal or administrative proceedings where such information is
relevant, or to properly provide the Services, operate or maintain its systems
or protect itself or its customers.

     . Critical Path reserves the right to terminate any Customer's or End
User's account if Critical Path learns that such Customer or End User has
provided Critical Path with false or misleading registration information.

Account and Password

     . Each Customer and End User is responsible for maintaining the
confidentiality of its account number and password and is responsible for all
uses of its account, whether or not authorized by the Customer or End User.

     . Customer or End User agrees to immediately notify Customer of any
unauthorized use of its account.


CONFIDENTIAL EXECUTION COPY           45
<PAGE>
 
Rights and Responsibilities

 . Certain violations of this AUP may subject Customer and/or End User to
criminal and/or civil liability.

 . Critical Path considers most instances of unsolicited bulk e-mail to be a
theft of Services and reserves the right to take appropriate actions against
originators of same, including terminating the applicable account(s) and suing
for damages.

 . Customer and End User agrees to indemnify and hold Critical Path, its
suppliers and their respective affiliates and agents, harmless from any claim,
action or demand, including reasonable attorneys' fees, made by any third party
due to, arising out of or related to Customer's or User's use of the Services or
the violation of this AUP, including without limitation the infringement by
Customer or End User, or any other user of the applicable account, of any
intellectual property or other right of any person or entity.

     . Nothing contained in this document shall be construed to limit action
Critical Path may take or remedies available to it in any way with respect to
any prohibited activity or conduct.  Critical Path reserves the right to take
any additional actions it may consider appropriate with respect to such activity
or conduct, including without limitation taking action to recover costs and
expenses of identifying offenders and removing them from Critical Path's network
or systems, and levying cancellation charges to cover costs in the event of
disconnection for the causes outlined in this AUP.  In addition, Critical Path
reserves the right to charge and/or sue for damages (including damage to
software, hardware and other equipment and the time and expense incurred in
repairing such damage) if any harm is done to its network or equipment which
requires repair or reconfiguration of any kind.

 . Non-enforcement of any term of this AUP does not constitute consent or waiver,
and Critical Path Inc. reserves the right to enforce such term at its sole
discretion.

-----------------------------------------------------------------------
DEFINITIONS

 . "Customer" refers to the business entity which has contracted with Critical
Path, Inc. for e-mail services. Each Customer may have multiple domain accounts
and each domain account may have one or more End User.

 . "End User" refers to the person, persons, or entity using a specific account
(designated by a unique e-mail address) within a domain controlled by the
Customer and operated by Critical Path, Inc.

------------------------------------------------------------------------

Selected Bibliography  (if you are concerned about spam and other uses of the
---------------------                                                        
Internet and email, the following websites might be of interest to you.
Critical Path does not make these sites available and makes no warranties or
representations regarding them.)

 . RFC 1855 "Netiquette Guidelines" (the "unwritten" rules)

 . Fight Spam on the Internet! (the central site for the anti-spam activist
community; includes filtering methods, example policies, and much more)

 . Coalition Against Unsolicited Commercial E-mail (the world's largest online
organization)

  . The Net Abuse FAQ (mainly deals with Usenet; maintained by a Critical Path
    employee)


CONFIDENTIAL EXECUTION COPY           46
<PAGE>
 
                                 TERMS OF USE
                                 -------------

                Please read the following agreement carefully.

     You must accept the agreement to be able to use the CUSTOMER Service.

1.  Acceptance of Terms of Use

CUSTOMER's mail service ("CUSTOMER Service") is provided free of charge to
registered users (each, a "User") under these Terms of Use. BY COMPLETING THE
REGISTRATION PROCESS AND CLICKING THE "I ACCEPT" BUTTON, YOU ARE INDICATING YOUR
AGREEMENT TO BE BOUND BY THESE TERMS OF USE.  These Terms of Use are the entire
agreement between you and CUSTOMER with respect to the services provided by
CUSTOMER.

2.  Privacy of Information

It is CUSTOMER's policy to respect the privacy of its Users.  CUSTOMER does not
censor or control the contents of its Users' email messages. You alone are
responsible for the contents of your messages, and the consequences of any such
messages.  As owner of the equipment and other resources used in providing the
CUSTOMER Service, CUSTOMER and its suppliers reserve the right to employ
blocking or filtering software or other monitoring devices or techniques if
deemed necessary or reasonable to detect and/or protect itself from spam with
respect to electronic communications received by Users from other persons or
entities.

CUSTOMER will cooperate with law enforcement and other legal authorities in
investigating claims of illegal activity and to report to law enforcement
officials any suspected illegal activity.

CUSTOMER will not release any personally-identifiable information regarding its
Users to any third party except to the extent necessary or appropriate to
cooperate with such law enforcement or other legal authorities, to comply with
applicable laws or regulations or in legal or administrative proceedings where
such information is relevant, or to properly provide the CUSTOMER Service,
operate or maintain its systems or protect itself or its customers. You agree
that CUSTOMER's judgment as to the validity of any court order or government
directive to disclose information shall be considered proper and final.
CUSTOMER reserves the right to terminate any User's account if CUSTOMER learns
that such User has provided CUSTOMER false or misleading registration
information.

3. Modifications of these Terms of Use

CUSTOMER may modify these Terms of Use from time to time in its sole discretion.
CUSTOMER will provide you with reasonable notice of any such changes, and your
continued use of the CUSTOMER Service will be deemed to constitute your
acceptance of any such changes.

4. CUSTOMER's Rights

CUSTOMER may modify or discontinue your account or the CUSTOMER Service with or
without notice, without liability to you or any third party.

5. Prohibited Activities


CONFIDENTIAL EXECUTION COPY           47
<PAGE>
 
The CUSTOMER Service may only be used for lawful purposes.  Transmission,
distribution, or storage of any information, data or material in violation of
any applicable law, regulation, ordinance or other rule imposed by any
governmental authority, is prohibited. This includes, but is not limited to,
material protected by copyright, trademark, trade secret, or other proprietary
right.


     You agree that you will not transmit or disseminate:  (i) advertising,
chain letters, spam, junk mail or any other type of unsolicited emailing
(whether commercial or informational) to persons or entities that have not
agreed to be part of such mailings; (ii) harassing, libelous, abusive,
threatening, obscene or otherwise objectionable materials or materials which
infringe or violate any third party's copyright, trademark, trade secret,
privacy or other proprietary or property right, or that could constitute a
criminal offense, give rise to civil liability or otherwise violate any
applicable law or regulation; or (iii) viruses or other harmful, disruptive or
destructive files.  You may not alter headers of email messages to conceal the
email address or prevent others from responding to the messages.

You agree that you will not use or attempt to use another person's or entity's
account, service or system without authorization from the owner, nor will you
interfere with the security of the CUSTOMER Service, system resources or
accounts or any network.  You may not abuse systems, or make use of the CUSTOMER
Service in a way that disrupts the normal use of CUSTOMER's system or services
for others.  This includes but is not limited to, running excessive numbers of
processes, attempting to disrupt the connections or other customers, consuming
excessive amounts of CPU time, memory or disk space, or running multiple
simultaneous logins.

Unsolicited advertisements or solicitations sent from other networks which
reference email accounts hosted by CUSTOMER will be treated as if they
originated from the referenced account, unless CUSTOMER knows, or has sufficient
evidence to believe, that the message originated with some unrelated party.

     Likewise, you may not post inappropriate messages to newsgroups.  Criteria
for whether a post is inappropriate include, but are not limited to, the written
charter/FAQ of the newsgroup, established Usenet conventions, the system
resources effected by the posting and applicable laws.  You are responsible for
determining whether or not a newsgroup permits the type of message you intend to
post.  You may not "flood" or disrupt Usenet groups, or cancel or modify
articles posted by others.

6.  Violations

If CUSTOMER and/or its suppliers become aware of possible violations, they may,
in their sole discretion, , initiate an investigation, suspend or terminate the
account, remove materials from its server, cancel newsgroup posts, issue a
warning, or take other responsive action.  You agree to respond in a timely
manner to any complaints.  CUSTOMER and its suppliers reserve the right to
assess a charge of $500.00 per complaint received by CUSTOMER or its suppliers
and to recover damages for such complaints for any harm done to the system or
service or for employee hours devoted to responding to complaints.   Nothing
contained in these Terms of Use shall be construed to limit the actions CUSTOMER
or its suppliers may take or remedies available to it in any way with respect to
any prohibited activity or conduct.

Certain violations of these Terms of Use may subject User to criminal and/or
civil liability.

Non-enforcement of any term of these Terms of Use does not constitute consent or
waiver, and CUSTOMER reserves the right to enforce such term at its sole
discretion.

7. Account and Password


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<PAGE>
 
You warrant that you are at least 18 years of age or older.  You are responsible
for maintaining the confidentiality of your account number and password.  You
are responsible for all uses of your account, whether or not authorized by you.
You agree to immediately notify CUSTOMER of any unauthorized use of your
account.

8. Disclaimer of Warranties

YOU EXPRESSLY AGREE THAT USE OF THE CUSTOMER SERVICE IS AT YOUR SOLE RISK. THE
CUSTOMER SERVICE IS PROVIDED ON AN "AS IS" AND "AS AVAILABLE" BASIS.

CUSTOMER DISCLAIMS ALL WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
WITHOUT LIMITATION ANY WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE OR NON-INFRINGEMENT.

CUSTOMER DOES NOT MAKE ANY WARRANTY THAT THE CUSTOMER SERVICE WILL MEET YOUR
REQUIREMENTS, OR THAT THE CUSTOMER SERVICE WILL BE UNINTERRUPTED, TIMELY,
SECURE, OR ERROR FREE; NOR DOES CUSTOMER MAKE ANY WARRANTY AS TO THE RESULTS
THAT MAY BE OBTAINED FROM THE USE OF THE CUSTOMER SERVICE OR AS TO THE ACCURACY
OR RELIABILITY OF ANY INFORMATION OBTAINED THROUGH THE CUSTOMER SERVICE.

YOU UNDERSTAND AND AGREE THAT ANY MATERIAL AND/OR DATA DOWNLOADED OR OTHERWISE
OBTAINED THROUGH THE USE OF THE CUSTOMER SERVICE IS AT YOUR OWN DISCRETION AND
RISK AND THAT YOU WILL BE SOLELY RESPONSIBLE FOR ANY DAMAGE TO YOUR COMPUTER
SYSTEM OR LOSS OF DATA THAT RESULTS FROM THE DOWNLOAD OF SUCH MATERIAL AND/OR
DATA.

CUSTOMER DOES NOT MAKE ANY WARRANTY REGARDING ANY GOODS OR SERVICES PURCHASED OR
OBTAINED THROUGH THE CUSTOMER SERVICE OR ANY TRANSACTIONS ENTERED INTO BY USE OF
OR THROUGH THE CUSTOMER SERVICE.

NO ADVICE OR INFORMATION, WHETHER ORAL OR WRITTEN, OBTAINED BY YOU FROM CUSTOMER
OR THROUGH THE CUSTOMER SERVICE SHALL CREATE ANY WARRANTY NOT EXPRESSLY MADE
HEREIN.

9. Limitation of Liability

CUSTOMER AND ITS SUPPLIERS SHALL NOT BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES, RESULTING FROM THE USE OR THE
INABILITY TO USE THE CUSTOMER SERVICE OR FOR THE COST OF PROCUREMENT OF
SUBSTITUTE GOODS AND SERVICES OR RESULTING FROM ANY GOODS OR SERVICES PURCHASED
OR OBTAINED OR MESSAGES RECEIVED OR TRANSACTIONS ENTERED INTO BY MEANS OF OR
THROUGH THE CUSTOMER SERVICE OR RESULTING FROM UNAUTHORIZED ACCESS TO OR
ALTERATION OF YOUR TRANSMISSIONS OR DATA, INCLUDING BUT NOT LIMITED TO, DAMAGES
FOR LOSS OF PROFITS, USE, DATA OR OTHER INTANGIBLE, EVEN IF CUSTOMER OR ITS
SUPPLIER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

10. Email Message Storage


CONFIDENTIAL EXECUTION COPY           49
<PAGE>
 
CUSTOMER does not assume any responsibility for the deletion or failure to store
email messages. If you exceed the maximum permitted storage space, CUSTOMER
reserves the right to delete email messages from the affected mailboxes, at its
discretion.

11. Promotional Messages

CUSTOMER and/or third parties may, from time to time, send email messages to you
containing advertisements, promotions, etc.  CUSTOMER does not make any
representation or warranty with respect to any such email messages or any goods
or services which may be obtained from such third parties, and you agree that
CUSTOMER shall have no liability with respect thereto.

12. Indemnification

You agree to indemnify and hold CUSTOMER, its suppliers and their respective
affiliates, officers, directors, employees and agents, harmless from any claim,
action or demand, including reasonable attorneys' fees, made by any third party
due to, arising out of or related to your use of the CUSTOMER Service or
violation of these Terms of Use, including without limitation the infringement
by you, or any other user of your account, of any intellectual property or other
right of any person or entity.

13. Applicable Law

These Terms of Use shall be governed by and construed in accordance with the
laws of the State of California, without giving effect to its conflict of laws
provisions.


                              I ACCEPT/I DECLINE


CONFIDENTIAL EXECUTION COPY           50
<PAGE>
 
                                   EXHIBIT G

                        OTHER WEBMAIL SERVICE PROVIDERS

                  (as of the Effective Date of the Agreement)

1.    Yahoo

2.    Excite

3.    IName

4.    Hot Mail

5.    Who Where




CONFIDENTIAL EXECUTION COPY           51          
