
<PAGE>
 
                                                                   EXHIBIT 10.19

CONFIDENTIAL TREATMENT REQUESTED. CONFIDENTIAL PORTIONS OF THIS DOCUMENT HAVE
BEEN REDACTED AND HAVE BEEN SEPARATELY FILED WITH THE COMMISSION.

                               CRITICAL PATH INC.
                               ------------------

                           E-MAIL SERVICES AGREEMENT
                           -------------------------


     THIS E-MAIL SERVICES AGREEMENT ("Agreement") is entered into as of the 14
day of September, 1998 ("Effective Date"), by and between Critical Path Inc.
       ---------                                                            
whose address is 320 First Street, San Francisco, CA 94105 (hereinafter referred
to as "Company"), and Sprint Communications Company L.P., a Delaware Limited
Partnership ("Sprint") whose address is 2330 Shawnee Mission Parkway, Westwood,
Kansas 66205.  The term of this Agreement shall consist of a Referral Period and
a Resale Period (with each term as defined below).  Section 1 of this Agreement
shall apply only to the Referral Period.  Sections 2 and 3 and all of the
Exhibits shall apply only to the Resale Period.  All remaining provisions of
this Agreement shall apply to both periods.

1.   Provision of Services During Referral Period.
     --------------------------------------------

     1.1.  Referral Period. Sprint may within its sole discretion, refer
           ---------------- 
           authorized Sprint Customers ("Referred Customers") to Company as a
           source for e-mail hosting services from the Effective Date of this
           Agreement until Sprint and Company implement the transition of their
           relationship to a resale arrangement ("Referral Period") set forth in
           Section 2. During the Referral Period, Company will negotiate the
           pricing and all other details related to e-mail hosting and related
           services ("Referral Services") directly with the Referred Customers.
           The Referral Services to be provided to Referred Customers shall
           include e-mail hosting, server and network maintenance and second-
           level (telephone and web-basedl) support to Referred Customers during
           Company's then-current hours of support, set up and web-based e-mail
           client. The parties agree that additional Referral Services may be
           provided by Company to Referred Customers provided such services are
           not in conflict with this Agreement. Company will make reasonable
           efforts to refer its customers to Sprint for their data and voice
           communication needs. Company will provide Referral Services directly
           to Referred Customers and, during the Referral Period, Sprint will
           not be liable for any charges incurred for such services. Company
           will provide invoicing of Referred Customers on Sprint approved co-
           branded forms if Sprint requests such an option. Sprint will incur
           the expense of providing such co-branded forms to Company for use in
           billing Referred Customers. Nothing in this Agreement requires Sprint
           to refer any Customers to Company during the Referral Period.

      1.2. Compensation: Each month during the Referral Period, Company shall
           pay Sprint a one-time Referral fee of $****/ Live Mailbox (as defined
           below): (i) which has been Live for at least three (3) months, and
           (ii) for which no Referral fee has yet been paid by Company to
           Sprint. As used in this paragraph, "Live Mailbox" means each mailbox
           (or group of mailboxes) made available for use by the Referred
           Customer during the Referral Period. Such amounts shall be payable by
           Company to Sprint within thirty (30) days of the last day of the
           month during the Referral Period. Sprint shall not pay financial
           compensation for Customers referred to Sprint by Company.

      1.3. Sprint Contact: During the Referral Period Company agrees to work in
           good faith with those Customers who may be referred by Sprint
           pursuant to this Agreement. Company agrees during the term of this
           Agreement that it shall not propose Internet services (including but
           not limited to web hosting, Internet access, or other IP services)
           available from Sprint ("Internet Services") from companies other than
           Sprint when working with Referred Customers. In the event that this
           Agreement is terminated during the Referral Period, Company agrees
           that it shall not solicit Referred Customers for Internet Services
           business for a period of one year after termination.

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     1.4.  Customer Ownership: Company understands that it is Sprint's intention
           to transition all Referred Customers acquired during the Referral
           Period as described in Section 2 of this Agreement. Therefore,
           Company shall track and report monthly those Referred Customers
           contacted and activating Referral Services as a result of Sprint
           references. Company also agrees that any agreements that it enters
           into with Referred Customers will allow assignment to Sprint at the
           time that the parties transition to the Resale Period. Additionally,
           Company will acquire two (2) toll free numbers from Sprint at
           Company's expense for Referral Sales and Customer Service use during
           the Referral Period.

      1.5. Company Information: Company agrees that Sprint may make public to
           potential customers written information obtained from Company during
           the Request For Information ("RFI") process utilized by Sprint in
           setting up this program. Such information from the RFI responses may
           be made available by Sprint to potential customers to inform them of
           the capabilities of Company in connection with making referrals to
           Company under this Section 1 ("Permitted Use"). Before Sprint makes
           any such disclosure of Company information, Sprint shall submit to
           Company a complete copy of the information Sprint intends to use for
           the Permitted Use, and Company shall approve such information and may
           add to or redact portions as Company deems necessary to protect its
           confidential or proprietary information. Sprint agrees to use only
           the information approved by Company for the Permitted Use. Company
           may request from time to time a copy of such RFI information used by
           Sprint under this Section.

      1.6. Conflict of Interest: Company agrees to advise Sprint of any conflict
           of interest that may arise during the course of this Agreement.
           Sprint acknowledges and agrees that any e-mail hosting services
           agreement which does not include referral services by Company that
           Company may enter into with another telecommunications provider or
           other competitor of Sprint shall not be deemed a conflict of interest
           under this Section.

2.   Provision of Services During Resale Period.
     ------------------------------------------ 

     2.1.  Services to be Provided During Resale Period. Within 30 days of
           --------------------------------------------
           Sprint's notice of intent to transition from referral relationship
           set forth in Section 1 ("Transition Notice"), Company shall provide,
           and Sprint hereby accepts, e-mail outsourcing services described in
           Exhibit A ("Services") which Sprint may resell to authorized Sprint
           Customers ("Customer(s)"). Sprint hereby agrees that it will access,
           re-sell and make the Services available to Customers only pursuant to
           Exhibit B-Terms of Use attached to this Agreement, as may be modified
           by either party from time to time upon notice to the other party, or
           under similar terms and conditions as agreed to in advance by both
           parties. Sprint agrees to notify, and to obtain binding consent from,
           Customer(s) of the Terms of Use prior to such Customer(s) initial use
           of the Services. Company shall make all services available and ready
           for resale by Sprint within thirty (30) days of Sprint's Transition
           Notice, excluding billing system integration requirements set forth
           by Sprint.

     2.2.  Set-Up Of Services For Customers Acquired During Resale Period.
           -------------------------------------------------------------- 
           Sprint shall provide to Company Customer(s) information and
           materials, such as the domain name, e-mail addresses and passwords,
           ("Customer Information") necessary for Company to transition
           Customer(s) current e-mail system to Company's e-mail messaging
           system through which Company provides the Services ("Company
           System"). Upon receipt of Customer Information, Company shall perform
           the set-up and other initial services before such Customer(s) will
           have access to the Company System. The parties agree to

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           work together to achieve a transition to the Company System,
           including branding the Web Mail Page as provided in Exhibit A, so
           that to the Customer(s) it is not apparent that the Services are
           being outsourced by Sprint to Company.

     2.3.  Transition of Referred Customers.   Company shall also transition all
           --------------------------------                                     
           Referred Customers acquired during the term of the Referral Period to
           Sprint under the terms and conditions of this Agreement within thirty
           (30) days of Sprint's written request for transition of Referred
           Customers. Company agrees to take all reasonable steps to accomplish
           said transition of Referred Customers to Sprint, including assigning
           to Sprint any agreements for Services that Company has entered into
           with Referred Customers.

     2.4.  Privacy.  Company has a corporate policy to respect the privacy of
           -------                                                           
           Customer(s) and their e-mail messages that are transmitted through
           the Company System or by means of the Services. Company will only
           access and disclose information as necessary to comply with
           applicable laws and government orders or requests, to provide the
           Services, to operate or maintain its systems or to protect itself or
           its clients. Company will maintain and adhere to industry accepted
           practices with respect to processes and procedures for maintaining
           the privacy of all Customer Information and e-mail provided to
           Company through the Services or otherwise under this Agreement and
           for compliance with all applicable privacy protection laws.

     2.5.  Compliance with Laws. Each party agrees to comply with all applicable
           --------------------                                                 
           laws, rules and regulations, including any Internet regulations or
           policies, privacy laws and applicable export laws, in its performance
           under this Agreement.

      2.6. Suspension or Termination. If Company becomes aware of or suspects
           ------------------------- 
           any violation of Exhibit C-Terms of Use by Sprint or any Customer,
           Company first shall attempt to notify Sprint and provide reasonable
           detail of such violation. The parties shall use best efforts to
           promptly resolve the matter. However, Company reserves the right to
           immediately suspend the provision of Services to Sprint or to such
           Customer as reasonably necessary to protect Company's interests.

      2.7. Modification of Services. Company reserves the right to modify its
           ------------------------
           network connectivity or peering arrangements to the Internet
           ("Connectivity") or modify or discontinue certain features or
           functionality of the Company System from time to time. However, if
           Company intends to modify the Company System in any way that, in
           Company's opinion, would significantly affect Customers' use of or
           ability to use the Services, then Company shall provide reasonable
           prior notice to Sprint of any such modification, no less than sixty
           (60) days prior to such modifications. If Company intends to modify
           the Connectivity of the Company System to the Internet for any
           reason, then Company shall provide prior notice to Sprint no less
           than thirty (30) days prior to such modification.

      2.8. Advertisements and Commercial Use. Sprint and Company may solicit
           ---------------------------------
           third parties for advertisements; however, Sprint shall maintain sole
           discretion over third party advertisements to be included for display
           on Sprint's "Web Mail Page" to Customer(s). Customer(s) shall have
           the option to receive ads or not. Customer(s) shall have the option
           to solicit and sell ad space for display to their user base only
           pursuant to the terms and conditions of Exhibit A, Section E.1.c. All
           parties shall share in the Advertising Revenue resulting therefrom as
           provided in Exhibit A. Each party shall be solely

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<PAGE>
 
           responsible for all obligations, liabilities and duties under any and
           all agreements with third parties with regard to such advertisements,
           unless otherwise expressly agreed in writing by the other party.
           Sprint agrees that it will resell the Services only bundled with
           other products and services and not as a stand-alone service or
           product offering. Sprint and Customer(s) agree that they will not
           make commercial use of, obtain advertising to be included on its Web
           Mail Page or otherwise generate income from, the Services or the
           Company System, other than as provided in Exhibit A or as permitted
           under the terms and conditions of this Agreement.

     2.9.  Year 2000 Compliance.  Company warrants that Company's provision of
           ---------------------                                              
           Services to Sprint, and any related deliverables provided to Sprint
           under this Agreement, will not be adversely affected by the
           occurrence or use of dates before, on, or after January 1, 2000 A.D.,
           including dates and leap years between the twentieth and twenty-first
           centuries ("Millennial Dates"). Any deliverables (including any
           software, hardware or firmware product(s) delivered by Company to
           Sprint) will without error or omission, create, receive, store,
           process and output (collectively, "Compute") information related to
           Millennial Dates. This warranty includes, without limitation, that
           the deliverables will accurately, and without performance
           degradation, Compute Millennial Dates, date-dependent data, date-
           related interfaces, or other date-related functions (including,
           without limitation, calculating, comparing, and sequencing such
           functions). At Sprint's request, Company will provide written
           evidence sufficient to demonstrate adequate testing and conversion of
           the deliverable to meet the foregoing requirements.

3.   Pricing and Payment During the Resale Period.
     -------------------------------------------- 

     3.1.  Pricing and Payment.  Exhibit A specifies Company's charges for the
           -------------------                                                
           Services to Sprint and other payment provisions. Sprint and/or
           Customer(s) shall be responsible for payment of any and all taxes
           (excluding taxes based on Company's net income) based upon the use or
           resale of the Services under this Agreement, to the appropriate
           taxing authority or jurisdiction.

     3.2   Current Prices. Subject to Section 3.2.1, Exhibit A sets forth
           --------------
           Company's current matrix of prices for the Services to be performed
           hereunder for the period commencing on the Effective Date and ending
           on the last day of the month containing the twelve month anniversary
           of the Effective Date ("Initial Pricing Period").

           3.1.1     Adjustments to Prices.

              3.1.1.1  If Company and Sprint mutually agree that Company shall
                       provide additional Services to Sprint or perform Services
                       not then covered by the price matrix, Company shall
                       revise Exhibit A accordingly, to add the applicable
                       prices for such Services.

              3.1.1.2  In the event Sprint requests variations of any of the
                       Services provided by Company hereunder as set forth in
                       Exhibit A and, in Company's reasonable judgement such
                       variation or variations (either individually or in the
                       aggregate) have a material effect on the prices set forth
                       in Exhibit A for the Services to be performed, Company
                       and Sprint shall agree to revise Exhibit A to set forth
                       prices for such Services which reflect such variation(s).

              3.1.1.3  Subject to the provisions of Section 3.3, Company shall
                       amend Exhibit A to adjust the Service prices set forth
                       thereon for the twelve month period following the Initial
                       Pricing Period and for each twelve month period
                       thereafter

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                       during the term of this Agreement upon written notice to
                       Sprint in each case not less than ninety (90) days prior
                       to commencement of such twelve month period.

     3.2   Market Testing. Sprint shall be entitled to market test Company
           --------------                                                 
           prices for Services set forth in Exhibit A hereto on a quarterly
           basis during the term of this Agreement and, in addition, at any time
           that such prices are adjusted by Company in accordance with Section
           3.2. The determination of Company price competitiveness is to be
           based upon the overall charges to Sprint by Company for Services
           being provided as described in Exhibit A. Such market testing is
           intended to confirm whether Company prices are competitive with the
           lowest end of the market consisting of quality, full turnkey E-mail
           Service providers with comparable volume, features, functionality and
           support. If prices are not competitive as reasonably shown by such
           market test and as agreed by Company, and Company has not remedied in
           thirty (30) days, Sprint may terminate this Agreement pursuant to
           Section 7.

     3.3  Reports and Audit. Each party shall submit with each of its payments
          -----------------    
          to the other party a detailed report of the calculation of each such
          payment. Each party will retain records relevant to its calculations
          of the payments made to the other party during the term of this
          Agreement and for a two (2) year period thereafter. Each party shall
          have the right, at its expense, acting through a certified public
          accountant, to examine and audit such records at all reasonable times,
          on at least ten (10) days notice to the other party, but no more than
          once every six (6) months.

4    Disclaimer of Warranties.
     ------------------------ 

     4.1  THE SERVICES ARE PROVIDED, AND THE COMPANY SYSTEM IS MADE AVAILABLE,
          BY COMPANY TO SPRINT AND CUSTOMERS "AS IS." COMPANY AND ITS SUPPLIERS
          MAKE NO WARRANTY OF ANY KIND, WHETHER EXPRESS OR IMPLIED, REGARDING
          THE SERVICES OR THE COMPANY SYSTEM AND SPECIFICALLY DISCLAIM THE
          WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
          AGAINST INFRINGEMENT, TO THE MAXIMUM EXTENT POSSIBLE BY LAW.

     4.2  Other than the services, processes and procedures to be followed by
          Company pursuant to EXHIBIT C Service Level Agreement, Company and its
          suppliers make no warranties regarding the quality, reliability,
          timeliness or security of the Services or the Company System or that
          the Services or the Company System will be uninterrupted or error
          free. Company and its suppliers assume no responsibility or liability
          for the deletion or failure to store, or to store properly, e-mail
          messages. Sprint and Customers assume the entire risk in downloading
          or otherwise accessing any data, files or other materials obtained
          from third parties as part of the Services or by means of the Company
          System, even if Sprint or Customer has paid for virus protection
          services from Company.

     4.3  Sprint shall be solely responsible for any warranties provided to
          Customers with respect to the Services or the Company System.


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5    Limitation of Liability.
     ----------------------- 

     5.1   IN NO EVENT SHALL EITHER PARTY, OR ITS SUPPLIERS, BE LIABLE TO THE
           OTHER PARTY FOR CONSEQUENTIAL, EXEMPLARY, INDIRECT, SPECIAL OR
           INCIDENTAL DAMAGES, INCLUDING, WITHOUT LIMITATION, LOST REVENUES OR
           PROFITS, EVEN IF THE PARTY OTHERWISE LIABLE HAS BEEN ADVISED OF THE
           POSSIBILITY OF SUCH DAMAGES.

      5.2  Company shall not be responsible for any delays, errors, failures to
           perform, interruptions or disruptions in the Services or the Company
           Systems caused by or resulting from any act, omission or condition
           beyond Company's reasonable control, whether or not foreseeable or
           identified, including without limitation acts of God, strikes,
           lockouts, riots, acts of war, governmental regulations, fire, power
           failure, earthquakes, severe weather, floods or other natural disease
           or Customer's or any Customer's third party's hardware, software or
           communications equipment or facilities.

      5.3  In the event of disruption of the Services or availability of the
           Company System for a continuous period longer than twenty-four (24)
           hours, Sprint's sole remedy shall be refund of a pro rata portion of
           the price paid for the affected Services during such period of
           disruption. Company's entire liability, and Sprint's and Customer's
           entire and exclusive remedy, under this Agreement for any damages
           from any cause whatsoever, regardless of form or action, whether in
           contract, negligence or otherwise, shall in no event exceed an amount
           equal to the price paid for the Services out of which the claim
           arose.

      6    Confidential Information. Each party agrees to keep confidential and
           ------------------------
           to use only for purposes of performing under this Agreement, any
           proprietary or confidential information of the other party disclosed
           pursuant to this Agreement which is appropriately marked as
           confidential or which would reasonably be considered of a
           confidential nature, and, except as otherwise permitted by Section 9
           of this Agreement, the terms of this Agreement and all negotiations
           relating thereto. The obligation of confidentiality shall not apply
           to information which is publicly available through authorized
           disclosure, is known by the receiving party at the time of disclosure
           as evidenced in writing, is rightfully obtained from a third party
           who has the right to disclose it, or which is required by law to be
           disclosed. Upon any termination of this Agreement, each party shall
           return to the other party all confidential information of the other
           party, and all copies thereof, in the possession, custody or control
           of the party.

7    Indemnification. Each party (the "Indemnitor") shall defend, indemnify, and
     ---------------
     hold the other party (the "Indemnitee") harmless from and against any
     claims, losses, actions, demands or damages, including reasonable
     attorney's fees, resulting from any act, omission, negligence, or
     performance under this Agreement by the Indemnitor, its Customers, agents
     or representatives. This indemnity shall not apply to the extent the
     portion of such claim, liability, loss, cost, damage or expense is the
     result of the negligence or willful misconduct of the Indemnitee, its
     clients, agents or representatives, or to the extent liability is
     disclaimed or limited by either party under this Agreement. The indemnity
     obligations set forth in this Section are contingent upon: (a) the
     Indemnitee giving prompt written notice to the Indemnitor of any such
     claim(s); (b) the Indemnitor having sole control of the defense or
     settlement of the claim; and (c) at the Indemnitor's request and expense,
     the Indemnitee cooperating in the investigation and defense of such
     claim(s).


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8    Term and Termination.
     -------------------- 

     8.1  Term. This Agreement shall continue in effect from the Effective Date
          ----
          for one (1) year period, and thereafter shall renew automatically for
          successive one (1) year periods unless either party gives the other
          party at least sixty (60) days prior written notice of its intent not
          to renew the Agreement.

     8.2  Termination for Convenience. Notwithstanding the foregoing, either
          ---------------------------
          party may terminate this Agreement at any time, without cause, upon
          one hundred-twenty (120) days prior written notice to the other party.

     8.3  Termination for Breach. Notwithstanding the foregoing, either party
          ----------------------
          may terminate this Agreement by giving to the other party written
          notice of such termination and an opportunity to cure within thirty
          (30) days after receipt of such notice, upon the occurrence of any of
          the following events: (i) the other party materially breaches or
          defaults in any of the material terms or conditions of this Agreement,
          (ii) the other party makes any assignment for the benefit of
          creditors, is insolvent or unable to pay its debts as they mature in
          the ordinary course of business, or (iii) any proceedings are
          instituted by or against the other party in bankruptcy or under any
          insolvency laws or for reorganization, receivership or dissolution.

     8.4  Effect of Termination. Upon any termination of this Agreement, Company
          ---------------------
          shall immediately cease providing all Services, and Sprint and
          Customers shall no longer have access to the Company System. Except in
          the event of termination for Sprint's breach, Company shall work with
          Sprint in the migration of its e-mail system back to its setup in
          existence immediately before the Effective Date of this Agreement.
          Thereafter, Company shall delete all stored e-mail messages of Sprint
          and Customers on the Company System. Within sixty (60) days of any
          termination of this Agreement, each party shall pay to the other all
          unpaid fees accrued prior to termination.

     8.5  Survival. Sections 3.1, 3.4, 4, 5, 6, 7, 8.4, 8.5 and 10 and Exhibit A
          --------
          (as to amounts accrued but unpaid and paragraph B.4) shall survive any
          expiration or termination of this Agreement.

9    Publicity and Demo Accounts.
     --------------------------- 

     9.1  Publicity. During the term of this Agreement, upon prior written
          --------- 
          consent of the other party, either party may promote its relationship
          in press releases, sales presentations, sales collateral, sales
          training and its web site. Neither party may without the other party's
          prior written consent issue any news releases, or any public
          announcement, denials or confirmations with respect to this Agreement
          or its subject matter.

     9.2  Demo Accounts.  During the term of this Agreement, Company shall
          -------------                                                   
          provide Sprint with access to a mutually-agreeable number of email
          accounts ("Demo Accounts"), at no additional charge, for use by Sprint
          in demonstrating the administrative and end


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          user features of the Services to Sprint's sales personnel and to
          Customers and potential Customers. Such Demo Accounts shall be
          available at the domain "sprint.cp.net" and shall include the features
          and functionality of the Services as generally available and in beta
          testing (which may be subject to a beta testing or evaluation
          agreement) by Company.

10   Miscellaneous.
     ------------- 

     10.1  Entire Agreement. This Agreement, together with all Exhibits and any
           ----------------
           Schedules accepted by Company, constitutes the entire agreement of
           the parties with respect to the subject matter of this Agreement.
           This Agreement supersedes any and all agreements, either oral or
           written, between the parties to this Agreement with respect to the
           subject of this Agreement. Except as otherwise expressly provided
           herein, this Agreement may be modified only by a writing signed by an
           authorized representative of each party.

     10.2  Notices. Notices under this Agreement shall be in writing and shall
           -------
           be deemed given when delivered personally, or by e-mail (with
           confirmation of receipt) or conventional mail (registered or
           certified, postage prepaid with return receipt requested). Notices
           shall be addressed to the parties at the addresses appearing in the
           introductory paragraph of this Agreement, but each party may change
           the address by written notice in accordance with this paragraph.

     10.3  Assignment. This Agreement shall be binding upon and inure to the
           ----------
           benefit of the subsidiaries, affiliates, successors and permitted
           assigns of the parties to this Agreement. Neither party may transfer,
           sublicense or otherwise assign this Agreement or any of its rights or
           obligations hereunder without the other party's prior written
           consent, which consent will not be unreasonably withheld.
           Notwithstanding the foregoing, either party may assign this Agreement
           to (i) any entity in which the party has a greater than fifty-percent
           (50%) equity ownership interest or of which the party has voting
           control, or (ii) to person or entity that buys fifty percent (50%) or
           more of that party's stock or all or substantially all of that
           party's assets.

    10.4   General Provisions. Nothing contained in this Agreement is intended
           ------------------
           or is to be construed to constitute Company and Sprint as partners or
           joint ventures or either party as an agent of the other. If any
           provision of this Agreement shall be declared invalid, illegal or
           unenforceable, such provision shall be reformed only to the extent
           necessary to effect the original intention of the parties, and all
           remaining provisions shall continue in full force and effect. No
           waiver of any rights hereunder shall be deemed to be a waiver of the
           same or other right on any other occasion.

    10.5   Dispute Resolution. Any dispute, controversy or claim concerning or
           ------------------
           relating to this Agreement shall be resolved in the following manner:
  
           10.5.1  The parties agree to use all reasonable efforts to resolve
                   the dispute through direct discussions. To that end, either
                   party may give the other party written notice of any dispute
                   not resolved in the normal course of business. Upon such
                   notice, the parties shall attempt in good faith to resolve
                   the dispute promptly by negotiation between executives who
                   have authority to settle the controversy and who are at a
                   higher level of management than the persons with direct
                   responsibility for administration of this Agreement.

           10.5.2  If the parties are unable to resolve the dispute by such
                   means within thirty (30) days of the notice date, or such
                   other time period as mutually


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                   agreed, then either party may commence arbitration pursuant
                   to the Rules of Commercial Arbitration of the American
                   Arbitration Association ("AAA"), as modified or supplemented
                   under this Section 10.5. The arbitration shall be governed by
                   the United States Arbitration Act, 9 U.S.C. Sec. 1, et. Seq.,
                   and judgment upon the award rendered by the arbitrator(s) may
                   be entered by any court with jurisdiction or application may
                   be made to such a court for judicial recognition and
                   acceptance of the award and any appropriate order including
                   enforcement. The arbitration proceedings will be held in San
                   Francisco, California, if initiated by Sprint, or in Kansas
                   City, Missouri, if initiated by Company, or at such other
                   location as the parties may agree.

           10.5.3  The arbitration proceedings contemplated by this Section
                   shall be as confidential and private as permitted by law. To
                   that end, the parties shall not disclose the existence,
                   contents or results of any proceedings conducted in
                   accordance with this Section, and materials submitted in
                   connection with such proceedings shall not be admissible in
                   any other proceedings, provided, however, that this
                   confidentiality pro vision shall not prevent a petition to
                   vacate or enforce an arbitral award, and shall not bar
                   disclosures required by law. The parties agree that any
                   decision or award results from proceedings in accordance with
                   this Section shall have no preclusive effect in any other
                   matter involving third parties.

           10.5.4  Notwithstanding any of the foregoing, either party may
                   request injunctive and equitable relief either from the
                   arbitrators or from a court in order to protect the
                   intellectual property rights or trade secrets of the party,
                   pending the resolution of the dispute by arbitration as
                   provided hereunder.

     10.1  Relationship of the Parties. This Agreement does not constitute or
           ---------------------------
           create a joint venture, pooling arrangement, partnership, agency or
           formal business organization of any kind. The Parties shall be
           independent contractors for all purposes at all times and neither
           Party shall act as or hold itself out as agent for the other or
           create or attempt to create liabilities for the other Party.

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


     CRITICAL PATH INC.                SPRINT COMMUNICATIONS COMPANY L.P.


By_______________________________      By______________________________

 
Its_______________________________     Its______________________________



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                                   EXHIBIT A
                                   ---------


                     SERVICES, CHARGES AND PAYMENT SCHEDULE
                     --------------------------------------

This Services and Charges Schedule is attached to and made a part of the E-mail
Services Agreement between Sprint and Company (the "Agreement") and is subject
to the terms and conditions of the Agreement.  This Exhibit A shall apply to
Services provided to Sprint during the Resale Period.


A.   Services Charges - Sprint agrees to pay Company the following amounts for
     ----------------                                                         
     the following Services during the Initial Pricing Period :


     1) POP3 e-mail hosting: Sprint will pay to Company a basic monthly POP
        -------------------   
        email hosting fee per active mailbox in accordance with the following
        tiered volume schedule:


          First 1,000 mailboxes        ****/mailbox/month
               1,001- 20,000           ****/mailbox/month
               20,001- 75,000          ****/mailbox/month
               75,001  150,000         ****/mailbox/month
               150,001 +               ****/mailbox/month

     EXAMPLE:  ****

              TOTAL INVOICE = ****

     Each POP3 mailbox includes the following features:

        .   Automated account administration via an Account Provisioning
            Protocol(APP), and a secure (SSL-based) Web interface for easy,
            instant individual account provisioning
        .   Company's state-of-the-art, Web-based email interface, branded to
            match Sprint's and/or Customer(s) look and feel
        .   **** MB of disk space
        .   Multiple domain hosting
        .   Segmentable, LDAP accessible directory services (to be available
            October 1, 1998)
        .   Domain administrator ability to send email to all users at a domain
        .   Search-the-Web capability
        .   Live, 24 x 7 Tier 2 support, and the assignment of a Company
            relationship manager to oversee Sprint's ongoing support needs
        .   A team of software developers dedicated to the continuing
            enhancement of email performance and functionality
        .   Seamless and ongoing introduction of new features, with minimal need
            for existing users or administrators to upgrade software or
            equipment
        .   Additional features in advance of or simultaneous with general
            availability from Company
        .   Send and receive attachments up to 4 MB
        .   Spam blocking

     Company's Web-based email Interface includes all POP3 features plus the
     following features:


                                                                         Page 10
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<PAGE>
 
        .   Company's customizable Web Mail interface offers Sprint and
            Customer(s) the opportunity to share in advertising revenue, as well
            as a chance to extend Sprint's brand.
        .   Send, receive, forward, and reply to email messages
        .   Create and manage folders and filters
        .   Customize preferences (signatures, return address, expandable email
            window, etc.)
        .   Change passwords
        .   Set up auto-forwarding and auto-response
        .   Use spell-check (general availability planned for 10/15/98) and
            create an address book
        .   Send and receive HTML formatted messages
        .   Additional features in advance of or simultaneous with general
            availability from Company

     2) Premium features: Sprint agrees to pay Company the following amounts
        ------------------                                                    
for the following premium features:
<TABLE>
<CAPTION>

Virus Protection                                                          TBD / Month / Mailbox
----------------------------------------------------------------------------------------------------------
<S>                                                             <C>
Certified mail                                                  TBD
----------------------------------------------------------------------------------------------------------
Return Receipt Delivery                                         TBD
----------------------------------------------------------------------------------------------------------
Archiving (storage > 5 MB)                                      **** / 5 extra MBs / Month / Mailbox
----------------------------------------------------------------------------------------------------------
Permanent Archiving                                             TBD - Available ****
----------------------------------------------------------------------------------------------------------
Mailing List Management                                         TBD - Available ****
----------------------------------------------------------------------------------------------------------
Groupware: calendaring, electronic forms                        TBD - Available ****
----------------------------------------------------------------------------------------------------------
Unified Messaging                                               TBD
----------------------------------------------------------------------------------------------------------
</TABLE>

    Company will attempt to provide reasonable advance notice to Sprint of
    additional premium features and their expected availability. Charges to
    Sprint for listed features not yet available and any additional features not
    listed that become available will be negotiated in good faith by both
    parties in advance of general availability if Sprint notifies Company that
    it wishes to order such features.

2)  IMAP:  TBD

3)  Billing Cycle: The billing cycle for computing all billable items of all
    --------------                                                          
    Company services shall, for the purposes of this Agreement, be for the
    period commencing on the first day of each month and ending on the last day
    of each month. As used in this Exhibit, "Live Mailboxes" means mailboxes (or
    group(s) of mailboxes) that have been tested, accepted and signed off by the
    Sprint Customer and available for use by such Customer under this Agreement.
    During the Resale Period, only Live Mailboxes that have been Live for at
    least five (5) calendar days of the first month in which such Mailboxes
    became Live shall be billable. Live Mailboxes will not include any mailboxes
    of Referred Customers that are transitioned during the Resale Period.

B.  Branding of Web Mail Page

    1.  Fees - Sprint will pay to Company a one-time fee of $**** for branding
        ----                                                                 
        Sprint's Web Mail Page. In addition, if Company performs branding of any
        Customer's Web Mail Page, Sprint will pay to Company a one-time fee of
        $**** for Company's branding of each such Web Mail Page to Customer's
        specifications. Any additional services or any customization above
        and


                                                                         Page 11
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*CONFIDENTIAL MATERIAL REDACTED AND FILED SEPARATELY WITH THE COMMISSION
<PAGE>
 
        beyond the basic branding and development of the Web Mail Page,
        automatic sign-up page, and signatures will be billed at $75 per hour,
        with a minimum of one hour per request.

2.   Provision, Development and Approval - Sprint shall provide Company with all
     -----------------------------------                                        
     text and images ("Branding Materials") necessary for Company to brand
     Sprint's or Customer's Web Mail Page. Sprint will ensure that Sprint and
     Customer(s) have full power and authority to provide to Company, and to
     authorize Company's use of, the Branding Materials provided by Sprint for
     branding the Web Mail Page, and Sprint agrees to defend and indemnify
     Company with respect to any claims arising from Company's use of such
     Branding Materials. Company shall develop the branded Web Mail Page using
     such Branding Materials and shall provide, or otherwise make available to
     Sprint and Customer, such developed Web Mail Page for review and approval,
     which approval shall not be unreasonably withheld, delayed or conditioned.
     Customer(s) approval shall be deemed given if Sprint does not provide to
     Company notice of its rejection of the branded Web Mail Page within 
     seventy-two (72) hours of Company's provision of it.

3.   Modifications - Once approved, Company shall only be obligated to make one
     -------------                                                             
     change to the look and feel of the branded Web Mail Page and the automatic
     sign-up page at no additional charge. Any further requested changes will be
     chargeable at the rate of $**** per hour with a minimum of one hour per
     request.

4.   Proprietary Rights - Sprint hereby grants, and Sprint will ensure
     ------------------                                               
     Customer(s) grants, to Company a non-exclusive, nontransferable, worldwide,
     royalty-free, irrevocable (during the term of the Agreement) license to
     reproduce, display, perform, modify, prepare derivative works of and
     otherwise use the Branding Materials for the purpose of branding Sprint's
     or Customer's Web Mail Page and making such Web Mail Page available through
     the Company Services to Customer(s) and Sprint. Customer(s) shall retain
     all other proprietary right it may have in and to the Branding Materials.
     Company shall retain all proprietary rights in and to the Company Services
     (not including the Branding Materials as incorporated into Customer(s) Web
     Mail Page) and all development tools, routines, subroutines, applications,
     software and other materials (not including the Branding Materials) that
     Company may use in connection with branding the Web Mail Page.

C. Support-Company shall provide 2nd tier telephone support to Sprint twenty-
   four (24) hours a day, seven (7) days a week. Company shall use reasonable
   efforts to respond to such requests for support. Sprint shall be responsible
   for first-level telephone support to Customers and for all other support not
   otherwise specified herein to Customers.

D. Payment by Sprint to Company-All fees for Company Services shall be
   applicable for any month, or portion thereof as defined in Section A of this
   Exhibit, in which such Services are rendered. All fees are payable by Sprint
   within thirty (30) days of the end of each month in accordance with this
   Schedule and the Agreement. In addition, if during the previous month,
   Company performed any work on the branding of the Web Mail Page as provided
   herein, Sprint shall include the applicable fees for such work in the next
   month's payment. Payments postmarked after the due date shall be subject to a
   late fee of one and one-half percent (1.5%) per month, or, if less, the
   maximum amount allowed by applicable law.

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<PAGE>
 
1.  Invoicing - Invoices shall be prepared in one (1) original and two (2)
    ---------                                                             
    copies submitted in accordance with the following instruction and shall
   reference Contract No. __________________ and Cost Center __________________.

                        Original Invoice:  Sprint
                        Accounts Payable - MOKCMD0401
                        Post OffIce Box 5409
                        Kansas City, Missouri 64131-5409
 
                        One Copy:  Sprint
                        Mark Dalton - MOKCMY0405
                        Partner Management
                        8330 Ward Parkway
                        Kansas City, Missouri 64105

                        One Copy:  Sprint
                        Tad Jones - MOKCMY0405
                        Product Manager
                        8330 Ward Parkway
                        Kansas City, Missouri 64105

E.   Advertising Revenues

1.   Sharing of Advertising Revenues - Sprint has the option of soliciting third
     -------------------------------                                           
     parties for advertising on the Web Mail Page. If Sprint chooses this
     option, the parties shall share in the Advertising Revenues as follows :

     a)  If Sprint obtains the advertising:
                    **** Sprint
                    **** Company

     b)  If Company obtains the advertising and its use is approved by
         Sprint:
                    **** Company
                    **** Sprint

     c) If either party obtains the advertising through a third party, the
        parties will share **** of the net advertising revenue.

2.   Payment - Sprint shall pay to Company its share of Advertising Revenues
     -------                                                               
     received by Sprint during the preceding month within ninety (90) days of
     the end of each month. Company shall pay Sprint its share of Advertising
     Revenues received by Company during the preceding month within ninety (90)
     days after the end of each month during the term of this Agreement. If, in
     prior remittances, the paying party included revenues in the calculation of
     Advertising Revenues, as to which during the preceding month the party
     granted credits or refunds, then the party may reduce the Advertising
     Revenues paid to the other party by the amount of any such credits or
     refunds.

3.   Definitions - As used in this Exhibits A and B, if either party obtains
     -----------                                                           
     Advertising Revenue through a third party, "Advertising Revenues" shall
     mean the revenue received from third party ("Advertisers") by either party
     from advertisements included on the Web Mail Page, less any commissions,
     credits, or refunds paid to Advertisers with respect to such revenues.

                                                                        Page 13
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<PAGE>
 
F.  Storage Capacity - Each basic mailbox provided hereunder shall have a
    maximum storage capacity of **** MBytes. Sprint may purchase from Company
    additional storage space for resale at then-current fees as defined in this
    Exhibit. Company shall notify Customer(s) and Sprint that Customer(s)
    mailbox is approaching or exceeds the maximum limit. Thereafter, if such
    Customer exceeds the maximum storage capacity for more than thirty (30) days
    beyond date of notification, Company may delete e-mail messages from the
    affected mailboxes, at Company's discretion.


                                                                        Page 14
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*CONFIDENTIAL MATERIAL REDACTED AND FILED SEPARATELY WITH THE COMMISSION
<PAGE>
 
                                   EXHIBIT B
                                   ---------

                                  TERMS OF USE
                                  ------------


Sprint's e-mail service ("Sprint Service") is provided to registered users
(each, a "User") under these Terms of Use. BY COMPLETING THE REGISTRATION
PROCESS, YOU ARE INDICATING YOUR AGREEMENT TO BE BOUND BY THESE TERMS OF USE.

Sprint's Acceptable Conduct Policy for Sprint INTERNET Products and Services

Sprint's Acceptable Conduct Policy (the "Policy") for Sprint IP Products and
Services is designed to help protect Sprint, Sprint's customers and the Internet
community in general from irresponsible or, in some cases, illegal activities.

Sprint IP customers shall not, nor shall they permit or assist others to abuse
or fraudulently use Sprint IP Products and Services, including but not limited
to the following:

1)  Sending unsolicited e-mail that causes complaints from the recipients of
    such unsolicited e-mail; or,

2)  Mailbombing (sending large quantities of unwanted or unsolicited e-mail to
    individual e-mail accounts); or,

3)  Sending 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; or,

4)  Sending 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,

5)  Sending viruses or other harmful, disruptive or destructive files; or,

6)  Unauthorized attempts by a user to gain access to any account or computer
    resource not belonging to that user (e.g., "spoofing"); or,

7)  Obtaining or attempting to obtain service by any means or device with intent
    to avoid payment; or,

8)  Unauthorized access, alteration, destruction, or any attempt thereof, of any
    information of any Sprint customers or end-users by any means or device; or,

9)  Knowingly engage in any activities that will cause a denial-of-service
    (e.g., synchronized number sequence attacks) to any Sprint customers or end-
    users; or,

10) Using Sprint's Products and Services to interfere with the use of the Sprint
    network by other customers or authorized users, or in violation of the law
    or in aid of any unlawful act.

It is Sprint's policy to respect the privacy of its Users.  Sprint does not, and
cannot, monitor, censor or edit the contents of User's e-mail messages. User
alone is responsible for the contents of User's messages, and the consequences
of any such messages.

User agrees that it will not use or attempt to use another person's or entity's
account, service or system without authorization from the owner, nor will User
interfere with the security of, or otherwise abuse, the Sprint Service, system
resources or accounts, or any network or another user's use or enjoyment of the
mail services.  User may not forge header or address information.  Sprint will
only access and disclose information as necessary to comply with applicable laws
and government orders or requests, to provide the services, to operate or
maintain its systems or to protect itself or its suppliers.  Sprint reserves the
right to terminate User's account if it becomes aware and determines, in
Sprint's sole discretion, that User is violating any of these Terms of Use.

                                                                        Page 15
                                 Confidential
<PAGE>
 
Each Sprint IP customer is responsible for the activities of its customer base
or end-users and, by accepting service from Sprint, is agreeing to ensure that
its customers abide by this Policy. Complaints about customers or end-users of a
Sprint IP customer will be forwarded to the Sprint IP customer's hostmaster for
action. If irresponsible or illegal activity continues, then the Sprint IP
customer's Products and Services may be subject to termination or other action
as Sprint deems appropriate without notice.

As stated in the terms and conditions for Sprint IP Products and Services,
Sprint has the right to terminate the account of an offending customer or take
other action as Sprint deems appropriate without notice (e.g., address
filtering).

Account and Password

 User is responsible for maintaining the confidentiality of its account number
 and password.  User shall be responsible for all uses of its account, whether
 or not authorized by User.  User agrees to immediately notify Sprint of any
 unauthorized use of its account.

Disclaimer of Warranties

 USER EXPRESSLY AGREES THAT USE OF THE SPRINT SERVICE IS AT USER'S SOLE RISK.
 THE SPRINT SERVICE IS PROVIDED ON AN "AS IS" AND "AS AVAILABLE" BASIS.

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

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

 USER UNDERSTANDS AND AGREES THAT ANY MATERIAL AND/OR DATA DOWNLOADED OR
 OTHERWISE OBTAINED THROUGH THE USE OF THE SPRINT SERVICE IS AT USER'S OWN
 DISCRETION AND RISK AND THAT USER WILL BE SOLELY RESPONSIBLE FOR ANY DAMAGE TO
 USER'S COMPUTER SYSTEM OR LOSS OF DATA THAT RESULTS FROM THE DOWNLOAD OF SUCH
 MATERIAL AND/OR DATA.

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

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

Limitation of Liability

 SPRINT 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 SPRINT 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 SPRINT SERVICE OR RESULTING FROM UNAUTHORIZED ACCESS TO OR
 ALTERATION OF USER'S TRANSMISSIONS OR DATA, INCLUDING BUT NOT LIMITED TO,
 DAMAGES FOR LOSS OF PROFITS, USE, DATA OR OTHER INTANGIBLE, EVEN IF SPRINT OR
 ITS SUPPLIER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

                                                                        Page 16
                                 Confidential
<PAGE>
 
E-mail Message Storage

  Sprint does not assume any responsibility for the deletion or failure to store
  e-mail messages. If User exceeds the maximum permitted storage space, Sprint
  reserves the right to delete e-mail messages from the affected mailboxes, at
  its discretion.

Promotional Messages

  Sprint and/or third parties may, from time to time, send e-mail messages to
  User containing advertisements, promotions, etc. Sprint does not make any
  representation or warranty with respect to any such e-mail messages or any
  goods or services which may be obtained from such third parties, and User
  agrees that Sprint shall have no liability with respect thereto.

Indemnification

  User agrees to indemnify and hold Sprint, 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 User's use of the Sprint
  Service or the violation of these Terms of Use by User, including without
  limitation the infringement by User, or any other user of User's account, of
  any intellectual property or other right of any person or entity.

Applicable Law

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

Sprint reserves the right to modify these terms of use at any time.

                                                                        Page 17
                                 Confidential
<PAGE>
 
                                   EXHIBIT C
                                   ---------

                            SERVICE LEVEL AGREEMENT

     This Exhibit C Service Level Agreement is attached to and made a part of
the E-mail Services Agreement between Sprint and Company (the "Agreement") and
is subject to the terms and conditions of the Agreement.  This Exhibit C shall
apply to Services provided to Sprint during the Resale Period.

1.  Performance

    Definition:  As used in this Exhibit, "system outage" means any unplanned
    ----------                                                               
    interruption in the provision of Company Services during which Customers are
    unable to access or use the Company Services and which is caused by a
    problem in the Company System and confirmed by Company. "System outage" does
    not include any interruptions in the Company Services caused by act,
    omission or condition beyond Company's reasonable control, such as acts of
    nature or any third party.

    Processing E-mails:  Monthly average server response time of less than 5
    ------------------                                                      
    seconds for 90% of requests. Measurement does not include network
    transmission time or delays. This average does not include any period of
    unforeseen, unsolicited bulk email messages that degrade service.

    Availability: Company will make all commercially reasonable attempts to
    ------------                                                           
    maintain 99.5% availability of all system services (not including regular
    maintenance intervals) at the following performance levels:

    .  SMTP accepting connections within **** seconds
    .  POP accepting connections within **** seconds
    .  Web-based email available and online ****%
    .  Account Provisioning System (APS) available and online ****%

    Maintenance Intervals: Current maintenance intervals are Monday mornings
    ---------------------
    from 12:00 AM to 3:00 AM Pacific Standard Time. Company will notify Sprint a
    minimum of fourteen (14) days in advance of changing this maintenance
    interval.

    Procedures for System Outages: In the event of a Customer-affecting
    -----------------------------
    scheduled outage (in which Customers will not be able to access and use the
    Company Services) is required, Company will send notification to Customers
    via e-mail no less than forty eight (48) hours in advance of the scheduled
    outage unless it is an emergency requiring immediate attention.

2.  Monitoring/Reporting

    Company shall include in all Customer records a Sprint Customer
    Identification code provided by Sprint. Company shall provide on a monthly
    basis customer reports sorted by Sprint Customer Identification code that
    includes the following information for each account:

    .   Number of mailboxes
    .   Number and type of premium services (as premium services are available)
    .   Number of messages sent/received per mailbox (Q1 '99)
    .   Number of Kbytes sent/received per mailbox (Q1 `99)
    .   Peak amount of storage used per mailbox (Q1 '99)
    .   Distribution of message sizes by Sprint Customer Identification (Q2 '99)

                                                                        Page 18
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*CONFIDENTIAL MATERIAL REDACTED AND FILED SEPARATELY WITH THE COMMISSION
<PAGE>
 
     Company shall provide a monthly Stewardship report that will track the
     performance metrics stated in Section 1 of this Exhibit.

     Company shall provide Sprint with monthly reports which document all
     Company System outages or enhancements made during such month. Each report
     shall have capacity planning information outlined [above] and include, at a
     minimum, the following additional information:

     Utilization and Performance:

     .   Company System uptime
     .   Number of new Sprint mailboxes
     .   Number of deleted Sprint mailboxes
     .   Total number of Sprint mailboxes
     .   Mean storage used for mailboxes
     .   Number of Company System outages
     .   Company System total downtime and average daily and monthly downtimes

  Specific Outage Report:
     .   Time of outage
     .   Length of outage
     .   Affected areas
     .   Reason for outage
     .   Long term remedy
     .   Person notified

  Enhancement:
     .   Reason for change
     .   Areas affected

  This information will be emailed to Sprint by the third working day of the
  month following the reported month.  Upon mutual agreement, the parties may
  add to or delete from this list of reports as appropriate.

3.  Escalation Procedures

Company shall notify Sprint or a Sprint designated agent in the event of a
system outage.  Company will send an email notice whenever possible.  In the
event that email is not working, or Company is otherwise unable to send an email
message, then Company will notify Sprint by telephone within 30 minutes of the
time that Company first learns of the outage.

     .   Sprint Notification:    Tad Jones
                                 PHONE:  816-854-2471
                                 FAX:  816-854-2623
                                 EMAIL:  tad.jones@mail.sprint.com

Status information, if known by Company, to include:
        .   reason for the outage; and
        .   estimated time for service restoration.

     If Customer experiences a system outage and has not been notified by
     Company, Sprint will contact the Technical Support staff at Company by
     pager at 415/764-6203 (or such other telephone number as provided by
     Company) for the latest status.

     Company will periodically notify Sprint with updated status for the
     duration of the outage.  Company will attempt to so update Sprint every two
     (2) hours.

                                                                        Page 19
                                 Confidential
<PAGE>
 
      Company will provide a post-incident summary that will include:

      cause of the problem; method used to correct the problem; and measures
      Company will take to prevent similar occurrences in the future.

    Company shall furnish necessary staff to provide the Services. Company shall
    use commercially reasonable efforts to provide Sprint with telephone access
    to an engineering staff member 24 hours a day 365 days a year. Upon
    notification of a problem with the Company System or the Services, Company
    shall evaluate and verify the problem and provide Sprint with a mutually
    agreeable time estimate for resolution of the problem. Company shall
    promptly commence remedial activities and use commercially reasonable
    efforts to complete the system outage resolution within the mutually agreed
    upon time estimate.

4.  Business Resumption

    In the event of a system outage, Company System will automatically switch
    processing from the primary server to a hot backup server in such a way as
    to not cause Customer(s) noticeable performance degradation as specified in
    Section 1 of this Exhibit.

5.  Sprint System Modifications

    Sprint agrees to notify Company no less than 72 hours in advance of any
    modifications and/or network configuration changes (including system
    maintenance) to, as well as upgrades and removal of devices that impact the
    production and network connectivity from, Sprint's system through which the
    Company Services are provided if they are outside of the scheduled Monday
    maintenance windows. If any such change will or could, in either party's
    opinion, result in incompatibility between the parties' respective systems
    or interruptions in the Company Services, then the parties shall work
    together to resolve any such issue before Sprint makes the change.

6.  Performance Review

    Company agrees to participate in periodic service performance reviews on a
    mutually agreed upon period or at either party's request. Each time cycle
    will be evaluated and proper personnel will be contacted if service levels
    are out of bounds. Some potential "triggers" currently include:

    .   Service response time is longer than a threshold
    .   Sudden spike in in/out-bound mail volume
    .   Load average sustained above a threshold
    .   Available disk space below a threshold
    .   Failed or interrupted tape backup
    .   Delivery logs showing an unusual pattern

7.  Backup Site

    Company shall provide a backup site for its primary message center which
    will be deployed in the event of a system outage with the primary message
    center and which will operate in accordance with Section 4 of this Exhibit.
    In the event of a West Coast disaster, Critical Path moves IP addresses to
    its East Coast Data Center. All protocols continue to work under a failover
    scenario, including but not limited to, POP, SMTP, IMAP, LDAP and webmail.
    Customers will not have access to stored messages in event of failover until
    primary service is restored. Such backup site is currently located in a
    facility of, Colocation Inc.,
                                                                        Page 20
                                 Confidential
<PAGE>
 
    located on the east coast in Laurel, Maryland. Colocation Inc. is a carrier-
    neutral co-location facility with facilities on par with our primary
    interconnection point, DIGITAL's Palo Alto Internet Exchange (PAIX) located
    in Palo Alto California.


                                                                        Page 21
                                 Confidential
