<DOCUMENT>
<TYPE>EX-99
<SEQUENCE>7
<FILENAME>d83242ex99.txt
<DESCRIPTION>FORM OF LETTER TO SHAREHOLDERS
<TEXT>

<PAGE>   1


                                                                      EXHIBIT 99

                              BARRET BANCORP, INC.

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

                    NOTICE OF SPECIAL MEETING OF SHAREHOLDERS
                     TO BE HELD ON __________________, 2001

TO THE SHAREHOLDERS:

      Notice is hereby given that a Special Meeting of the shareholders of
Barret Bancorp, Inc. ("Barret") will be held at 9105 Barret Road, Millington,
Tennessee 38053, on _____________, 2001, at _____ o'clock __.m., local time, for
the purpose of considering and voting on the following matters, all as more
fully described in the accompanying Proxy Statement:

        (1) Approval of the Merger Agreement dated as of December 12, 2000,
among Barret, Peoples Bank ("Peoples"), Somerville Bank & Trust Company
("Somerville"), Trustmark Corporation ("Trustmark") and Trustmark National Bank
("Trustmark Bank") which provides for the Merger of Barret with and into
Trustmark and the merger of Peoples with and into Trustmark Bank.

        (2) Transaction of such other business as may properly come before the
Special Meeting or any adjournments thereof.

        Only those shareholders of record at the close of business on
______________, 2001, shall be entitled to notice of and to vote at the Special
Meeting.

                                              BY ORDER OF THE BOARD OF DIRECTORS



                                              Graves C. Leggett, Secretary

<PAGE>   2


                              BARRET BANCORP, INC.
                               _____________, 2001

Dear Shareholders:

        You are cordially invited to attend a Special Meeting (the "Special
Meeting") of the Shareholders of Barret Bancorp, Inc. ("Barret") to be held at
9105 Barret Road, Millington, Tennessee 38053 on ____________, 2001, at ______
__.m., local time.

        At the Special Meeting, you will be asked to approve the Merger
Agreement dated as of December 12, 2000, (the "Merger Agreement"), among Barret,
Trustmark Corporation ("Trustmark"), Trustmark National Bank ("Trustmark Bank"),
Peoples Bank ("Peoples") and Somerville Bank & Trust Company ("Somerville")
pursuant to which, among other things (a) Barret will merge with and into
Trustmark (the "Merger"), and (b) Peoples will merge with and into Trustmark
Bank.

        Upon consummation of the Merger, the holders of each share of Barret
will have the right to elect to convert those shares into cash in the amount of
$9,733 per Barret share, shares of the common stock of Trustmark, or some
combination of cash and Trustmark shares.

        The number of shares of Trustmark common stock which you will be
entitled to receive in exchange for each Barret share converted into Trustmark
common stock (the "Exchange Ratio") will be determined on _____________, 2001.
The Exchange Ratio is equal to $9,733 divided by the average closing price of
Trustmark common stock over the five consecutive trading days ending three days
prior to the Special Meeting date. You can find out the Exchange Ratio by
contacting Denna Krosp at Barret no more than two days prior to the Special
Meeting.

        Unless you exercise your right to receive cash for some or all of your
Barret shares, on the effective date of the Merger your Barret shares will be
converted into Trustmark common stock, except to the extent you receive cash in
lieu of fractional shares.

        Only those shareholders of record at the close of business on
____________, 2001, will be entitled to notice of and to vote at the Special
Meeting.

        YOUR BOARD OF DIRECTORS HAS UNANIMOUSLY APPROVED THE MERGER AGREEMENT
AND RECOMMENDS THAT YOU VOTE FOR APPROVAL OF THE MERGER AGREEMENT.

        The Board believes, based on its analysis, that the proposed Merger is
in the best interests of Barret's shareholders.

        Accompanying this letter, you will find a Notice of Special Meeting of
Shareholders, a Proxy Statement relating to the Special Meeting, a Proxy and an
Election Form. The Proxy Statement more fully describes the Merger and includes
information about Barret, Peoples, Somerville, Trustmark and Trustmark Bank.

        If you wish to vote in favor of the Merger please sign, date and return
the enclosed proxy whether or not you plan to attend the Special Meeting. The
prompt return of your signed proxy will assist Barret in minimizing the expense
of soliciting proxies. Your proxy may be revoked at any time prior to the vote
at the Special Meeting by notice to the Secretary of Barret, by execution and
delivery of a later dated proxy or by revoking the proxy in person at the
Special Meeting.

                                     Very truly yours,

                                     ------------------------------------------
                                     John P. Douglas, Jr.
                                     Chairman of the Board

                                     ------------------------------------------
                                     Charles M. Ennis
                                     President and CEO

<PAGE>   3


                                      PROXY

                              Barret Bancorp, Inc.
                                 Millington, TN

                         SPECIAL MEETING OF SHAREHOLDERS
                               ____________, 2001

        The undersigned hereby appoint(s) John P. Douglas, Jr. and Charles M.
Ennis or either of them, the true and lawful attorneys-in-fact for the
undersigned, with full power of substitution, to vote as proxies for the
undersigned at a Special Meeting of shareholders of Barret Bancorp, Inc.
("Barret") to be held at 9105 Barret Road, Millington, TN 38053, at _____
o'clock __.m., local time, on ______________, 2001, and at any and all
adjournments thereof, the number of shares of Barret held by the undersigned on
_________, 2001, (the "Record Date") which the undersigned would be entitled to
vote if then personally present, for the following purposes:

        1.     Approval of the Merger Agreement dated as of December 12, 2000
which provides for the Merger of Barret with and into Trustmark.

      [ ] Approve            [ ] Disapprove             [ ] Abstain

        2.     In their discretion the proxies are authorized to vote on such
other business as may properly come before the Special Meeting or any
adjournments thereof.

        THIS PROXY, WHICH IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS OF
BARRET, WILL BE VOTED FOR PROPOSAL 1 UNLESS A CONTRARY DIRECTION IS INDICATED,
IN WHICH CASE IT WILL BE VOTED AS DIRECTED. THE PROXIES INTEND TO VOTE ON ANY
OTHER BUSINESS COMING BEFORE THE SPECIAL MEETING PURSUANT TO THE AUTHORITY
GRANTED IN PARAGRAPH 2 IN ACCORDANCE WITH THE DIRECTION OF A MAJORITY OF THE
BOARD OF DIRECTORS OF BARRET.

        Your vote is important. Accordingly, even if you plan to attend the
Special Meeting, please date the Proxy and sign your name exactly as it appears
on the stock records of Barret and return this Proxy to Barret in the enclosed
envelope. When shares are held by joint tenants, both are requested to sign.
This Proxy may be revoked prior to its exercise by following the procedures set
out in the attached Proxy Statement. When signing as attorney, executor,
administrator, trustee or guardian, please give full title. If signed as a
corporation, please sign full corporate name by authorized officer.

        ______________________         Signature

        ______________________         Date

        ______________________         Signature if held jointly

        ______________________         Date

        PLEASE MARK, SIGN, DATE AND RETURN THIS PROXY PROMPTLY, USING THE
                               ENCLOSED ENVELOPE.



<PAGE>   4

                              Barret Bancorp, Inc.

                                Form of Election

     As provided for in the Merger Agreement dated as of December 12, 2000 among
Trustmark Corporation, Trustmark National Bank, Barret Bancorp, Inc., Peoples
Bank and Somerville Bank & Trust Company, the undersigned shareholder of Barret
Bancorp, Inc. hereby elects to receive the consideration designated below for
each share of the common stock of Barret Bancorp, Inc. held of record by the
undersigned as of ________________, 2001, which is the date of the Barret
Bancorp, Inc. special shareholders' meeting called to vote on the proposed
merger of Barret Bancorp, Inc. with Trustmark Corporation:

Mark Election
Desired:


-----------    1. ALL CASH ELECTION. I would like to be paid cash in the amount
               of $9,733 for each of my shares of Barret Bancorp, Inc. common
               stock.


-----------    2. ALL STOCK ELECTION. I would like to receive the number of
               shares of the common stock of Trustmark Corporation equal to the
               Exchange Ratio for each of my shares of Barret Bancorp, Inc.
               common stock.


-----------    3. COMBINATION ELECTION. I would like to be paid cash in the
               amount of $9,733 for ___________ of my shares of Barret Bancorp,
               Inc. common stock and receive the number of shares of the common
               stock of Trustmark Corporation equal to the Exchange Ratio for
               _______ of my shares of Barret Bancorp, Inc. common stock.

     This Form of Election must be received at Barret Bancorp, Inc. on or before
______________, 2001, which is the date of the Barret Bancorp, Inc. special
shareholders' meeting. Please send the Form of Election to the attention of
Denna Krosp, Barret Bancorp, Inc., 9105 Barret Road, Millington, Tennessee
38053.

     When shares are held by joint tenants, both are requested to sign. When
signing as attorney, executor, administrator, trustee or guardian, please give
full title. If signed as a corporation, please sign full corporate name by
authorized officer.

                                           ------------------------------------
                                           Shareholder                 Date



                                           ------------------------------------
                                           Shareholder                 Date




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