<PAGE>

                                                                     Exhibit 3.1

                       RESTATED ARTICLES OF INCORPORATION

                                       OF

                                 ZIX CORPORATION

                                   ARTICLE ONE

     Zix Corporation (the "Corporation"), pursuant to the provisions of Article
4.07 of the Texas Business Corporation Act, as amended, hereby adopts these
restated articles of incorporation which accurately copy the articles of
incorporation and all amendments thereto that are in effect to date and such
restated articles of incorporation contain no other change in any provision
thereof.

                                   ARTICLE TWO

     The restated articles of incorporation were adopted by resolution of the
Board of Directors of the Corporation on October 26, 2005.

                                  ARTICLE THREE

     The articles of incorporation and all amendments thereto are hereby
superseded by the following restated articles of incorporation which accurately
copy the entire text thereof:

                [Remainder of this page intentionally left blank]


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<PAGE>

                       RESTATED ARTICLES OF INCORPORATION

                                       OF

                                ZIX CORPORATION

                                   ARTICLE I

     The name of the Corporation is Zix Corporation.

                                   ARTICLE II

     The period of its duration is perpetual.

                                  ARTICLE III

     The purpose for which the Corporation is organized is to engage in any act,
activity or business for which corporations may be organized under the Texas
Business Corporation Act, as the same exists or may hereafter be amended;
provided, however, the Corporation shall not be authorized to transact any
business in this State which is prohibited by Article 2.01-B of the Texas
Business Corporation Act.

                                   ARTICLE IV

     The total number of shares of capital stock which the Corporation shall
have the authority to issue is One Hundred Seventy-Five Million (175,000,000)
shares of Common Stock, $.0l par value, and Ten Million (10,000,000) shares of
Preferred Stock, $1.00 par value. The Board of Directors of the Corporation is
authorized, subject to limitations prescribed by law and the provisions of this
Article IV, to provide for the issuance of the Preferred Stock from time-to-time
in one or more series, to establish the number of shares to be included in each
series, and to fix the designations, powers, relative rights, qualifications,
preferences, limitations and restrictions of the shares of each such series not
fixed hereby.

                                    ARTICLE V

     No stockholder of the Corporation shall, by reason of his holding shares of
any class of capital stock of the Corporation, have any preferential right to
purchase or subscribe to any shares of any class of capital stock of the
Corporation, or any notes, debentures, bonds, warrants, options or other
securities of the Corporation, now or hereafter to be authorized.


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<PAGE>

                                   ARTICLE VI

     No shareholder of the Corporation will be entitled to cumulative voting
with respect to the election of directors.

                                   ARTICLE VII

     The Corporation will not commence business until it has received for the
issuance of its shares consideration of the value of at least One Thousand
Dollars ($1,000.00), consisting of money, labor done or property actually
received.

                                  ARTICLE VIII

     The address of the registered office of the Corporation is 2711 N. Haskell
Avenue, Suite 2300, LB 36, Dallas, Texas 75204, and the name of its registered
agent at such address is Ronald A. Woessner.

                                   ARTICLE IX

     The number of directors from time to time constituting the Board of
Directors of the Corporation shall be fixed in the manner provided in the Bylaws
of the Corporation. The names of the persons currently serving as directors of
the Corporation are:

<TABLE>
<CAPTION>
      Name                      Address
----------------------   ----------------------
<S>                      <C>
Richard D. Spurr         2711 N. Haskell Avenue
                         Suite 2300, LB 36
                         Dallas, Texas 75204

Charles N. Kahn III      2711 N. Haskell Avenue
                         Suite 2300, LB 36
                         Dallas, Texas 75204

Michael E. Keane         2711 N. Haskell Avenue
                         Suite 2300, LB 36
                         Dallas, Texas 75204

James S. Marston         2711 N. Haskell Avenue
                         Suite 2300, LB 36
                         Dallas, Texas 75204

Antonio R. Sanchez III   2711 N. Haskell Avenue
                         Suite 2300, LB 36
                         Dallas, Texas 75204
</TABLE>


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<PAGE>

<TABLE>
<S>                      <C>
Paul E. Schlosberg       2711 N. Haskell Avenue
                         Suite 2300, LB 36
                         Dallas, Texas 75204

Dr. Ben G. Streetman     2711 N. Haskell Avenue
                         Suite 2300, LB 36
                         Dallas, Texas 75204
</TABLE>

                                    ARTICLE X

     A director of the Corporation shall not be personally liable to the
Corporation or its shareholders for monetary damages for breach of fiduciary
duty as a director, except liability for (i) any breach of the director's duty
of loyalty to the Corporation or its shareholders, (ii) any act or omission not
in good faith or which involves intentional misconduct or a knowing violation of
law, (iii) any transaction from which the director derived any improper personal
benefit, (iv) any act or omission where the liability of the director is
expressly provided for by statute; or (v) any act related to an unlawful stock
repurchase or payment of a dividend. If the Texas Business Corporation Act or
other applicable law of the State of Texas is amended after the filing of these
Restated Articles of Incorporation to authorize corporate action further
eliminating or limiting the personal liability of directors, then the liability
of a director of the Corporation shall be eliminated or limited to the fullest
extent permitted by the Texas Business Corporation Act or other applicable law
of the State of Texas, as so amended.

     Any repeal or modification of the foregoing paragraph by the shareholders
of the Corporation shall not adversely affect any right or protection of a
director of the Corporation existing at the time of such repeal or modification.

                                   ARTICLE XI

     A. Each person who was or is made a party or is threatened to be made a
party to or is otherwise involved in any action, suit or proceeding, whether
civil, criminal, administrative or investigative (hereinafter a "proceeding"),
by reason of the fact that he or she, or a person of whom he or she is the legal
representative, is or was a director or officer of the Corporation or is or was
serving at the request of the Corporation as a director or officer of another
corporation or of a partnership, joint venture, trust or other enterprise,
including service with respect to an employee benefit plan (hereinafter an
"indemnitee"), whether the basis of such proceeding is alleged action in an
official capacity as a director or officer or in any other capacity while
serving as a director or officer shall be indemnified and held harmless by the
Corporation to the fullest extent authorized by the Texas Business Corporation
Act or other applicable law of the State of Texas, as the same exists or may
hereafter be amended (but, in the case of any such amendment, only to the extent
that such amendment permits the Corporation to provide broader indemnification
rights than permitted prior thereto), against all expense, liability and loss
(including, without limitation, attorneys' fees, judgments, fines, ERISA excise
taxes or penalties and amounts paid or to be paid in settlement) reasonably
incurred or suffered by such indemnitee in connection therewith and such
indemnification shall continue as to an indemnitee who has


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<PAGE>

ceased to be a director or officer and shall inure to the benefit of the
indemnitee's heirs, executors and administrators; provided, however, that,
except for a proceeding brought by an indemnitee to enforce his rights to
indemnification, the Corporation shall indemnify any such indemnitee in
connection with a proceeding (or part thereof) initiated by such indemnitee only
if such proceeding (or part thereof) was authorized by the Board of Directors of
the Corporation. The right to indemnification conferred in this Article XI shall
be a contract right and shall include the right to be paid by the Corporation
the expenses incurred in defending any such proceeding in advance of its final
disposition (hereinafter an "advancement of expenses"); provided, however, that,
if the Texas Business Corporation Act or other applicable law of the State of
Texas requires, an advancement of expenses incurred by an indemnitee in his or
her capacity as a director or officer (and not in any other capacity in which
service was or is rendered by such indemnitee, including, without limitation,
service to an employee benefit plan) shall be made only upon delivery to the
Corporation of an undertaking (hereinafter an "undertaking"), by or on behalf of
such indemnitee, to repay all amounts so advanced if it shall ultimately be
determined by final judicial decision from which there is no further right to
appeal (hereinafter a "final adjudication") that such indemnitee is not entitled
to be indemnified for such expenses under this Article or otherwise.

     B. If a claim under this Article XI is not paid in full by the Corporation
within a reasonable time after a written claim has been received by the
Corporation, the indemnitee may at any time thereafter bring suit against the
Corporation to recover the unpaid amount of the claim. If successful in whole or
in part in any such suit, or advancement of expenses pursuant to the terms of an
undertaking, the indemnitee shall be entitled to be paid also the expense of
prosecuting or defending such suit. In (i) any suit brought by the indemnitee to
enforce a right to indemnification hereunder (but not in a suit brought by the
indemnitee to enforce a right to an advancement of expenses) it shall be a
defense that, and (ii) in any suit by the Corporation to recover an advancement
of expenses pursuant to the terms of an undertaking the Corporation shall be
entitled to recover such expenses upon a final adjudication that, the indemnitee
has not met the applicable standard of conduct set forth in the Texas Business
Corporation Act or other applicable law of the State of Texas. Neither the
failure of the Corporation (including its Board of Directors, independent legal
counsel or its stockholders) to have made a determination prior to the
commencement of such suit that indemnification met the applicable standard of
conduct set forth in the Texas Business Corporation Act or other applicable law
of the State of Texas, nor an actual determination by the Corporation (including
its Board of Directors, independent legal counsel, or its shareholders) that the
indemnitee has not met such applicable standard of conduct, shall create a
presumption that the indemnitee has not met the applicable standard of conduct
or, in the case of such a suit brought by the indemnitee, be a defense to such
suit. In any suit brought by the indemnitee to enforce a right to
indemnification or to an advancement of expenses hereunder or by the Corporation
to recover an advancement of expenses pursuant to the terms of an undertaking,
the burden of proving that the indemnitee is not entitled to be indemnified, or
to such advancement of expenses, under this Article XI or otherwise shall be on
the Corporation.

     C. The rights to indemnification and to the advancement of expenses
conferred in this Article XI shall not be exclusive of any other right which any
person may have or hereafter


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acquire under these Articles of Incorporation or any bylaw, agreement, vote of
shareholders or disinterested directors or otherwise.

     D. The Corporation may maintain insurance, at its expense, to protect
itself and any director or officer of the Corporation or another corporation,
partnership, joint venture, trust or other enterprise against any expense,
liability or loss, whether or not the Corporation would have the power to
indemnify such person against such expense, liability or loss under the Texas
Business Corporation Act or other applicable law of the State of Texas.

     E. The Corporation may, to the extent authorized from time to time by the
Board of Directors, grant rights to indemnification and to the advancement of
expenses to any employee or agent of the Corporation to the fullest extent of
the provisions of this Article XI with respect to the indemnification and
advancement of expenses of directors and officers of the Corporation.

                                   ARTICLE XII

     The initial Bylaws of the Corporation shall be adopted by the Board of
Directors. The power to alter, amend or repeal the Bylaws or adopt new Bylaws is
vested in the Board of Directors.

     IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 3rd day
of November 2005.


                                         /s/ Ronald A. Woessner
                                         ---------------------------------------
                                         Ronald A. Woessner
                                         Sr. Vice President, General Counsel and
                                         Secretary


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