<PAGE>

                                                                     EXHIBIT 4.2

NEITHER THESE SECURITIES NOR THE SECURITIES INTO WHICH THESE SECURITIES ARE
EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR
THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM
REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES
ACT"), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN
AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION
REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH APPLICABLE STATE
SECURITIES LAWS AS EVIDENCED BY A LEGAL OPINION OF COUNSEL TO THE TRANSFEROR TO
SUCH EFFECT, THE SUBSTANCE OF WHICH SHALL BE REASONABLY ACCEPTABLE TO THE
COMPANY. THESE SECURITIES AND THE SECURITIES ISSUABLE UPON EXERCISE OF THESE
SECURITIES MAY BE PLEDGED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT OR OTHER
LOAN SECURED BY SUCH SECURITIES.

                                 ZIX CORPORATION

                                     WARRANT

Warrant No. [  ]                        Date of Original Issuance: June 24, 2003

         Zix Corporation, a Texas corporation (the "COMPANY"), hereby certifies
that, for value received, [ ] or its registered assigns (the "HOLDER"), is
entitled to purchase from the Company up to a total of [ ](1) shares of common
stock, par value $.01 per share (the "COMMON STOCK"), of the Company (each such
share, a "WARRANT SHARE" and all such shares, the "WARRANT SHARES") at an
exercise price equal to $4.96 per share (as adjusted from time to time as
provided in Section 9, the "EXERCISE PRICE"), at any time and from time to time
from and after the date hereof and through and including June 24, 2007 (the
"EXPIRATION DATE"), and subject to the following terms and conditions:

         1.       Definitions. In addition to the terms defined elsewhere in
this Warrant, capitalized terms that are not otherwise defined herein shall have
the meanings given to such terms in the Securities Purchase Agreement of even
date herewith to which the Company and the original Holder are parties (the
"PURCHASE AGREEMENT").

         2.       Registration of Warrant. The Company shall register this
Warrant, upon records to be maintained by the Company for that purpose (the
"WARRANT REGISTER"), in the name of the record Holder hereof from time to time.
The Company may deem and treat the registered Holder

------------------------------------
1        The number of shares of Common Stock equal to 20% of the quotient
         obtained by dividing the Investment Amount of such Purchaser by $4.96.

<PAGE>

of this Warrant as the absolute owner hereof for the purpose of any exercise
hereof or any distribution to the Holder, and for all other purposes, absent
actual notice to the contrary.

         3.       Registration of Transfers. The Company shall register the
transfer of any portion of this Warrant in the Warrant Register, upon surrender
of this Warrant, with the Form of Assignment attached hereto duly completed and
signed, to the Company at its address specified herein. Upon any such
registration or transfer, a new Warrant to purchase Common Stock, in
substantially the form of this Warrant (any such new Warrant, a "NEW WARRANT"),
evidencing the portion of this Warrant so transferred shall be issued to the
transferee and a New Warrant evidencing the remaining portion of this Warrant
not so transferred, if any, shall be issued to the transferring Holder. The
acceptance of the New Warrant by the transferee thereof shall be deemed the
acceptance by such transferee of all of the rights and obligations of a holder
of a Warrant.

         4.       Exercise and Duration of Warrants. This Warrant shall be
exercisable by the registered Holder at any time and from time to time on or
after the date hereof to and including the Expiration Date. At 6:30 p.m., New
York City time on the Expiration Date, the portion of this Warrant not exercised
prior thereto shall be and become void and of no value. The Company may not call
or redeem all or any portion of this Warrant without the prior written consent
of the Holder.

         5.       Delivery of Warrant Shares.

                  (a)      To effect conversions hereunder, the Holder shall not
be required to physically surrender this Warrant unless the aggregate Warrant
Shares represented by this Warrant is being exercised. Upon delivery of the
Exercise Notice to the Company (with the attached Warrant Shares Exercise Log)
at its address for notice set forth herein and upon payment of the Exercise
Price multiplied by the number of Warrant Shares that the Holder intends to
purchase hereunder, the Company shall promptly (but in no event later than three
Trading Days after the Date of Exercise (as defined herein)) issue and deliver
to the Holder, a certificate for the Warrant Shares issuable upon such exercise,
which, unless otherwise required by the Purchase Agreement, shall be free of
restrictive legends. The Company shall, upon request of the Holder and
subsequent to the date on which a registration statement covering the resale of
the Warrant Shares has been declared effective by the Securities and Exchange
Commission, use its best efforts to deliver Warrant Shares hereunder
electronically through the Depository Trust Corporation or another established
clearing corporation performing similar functions, if available, provided, that,
the Company may, but will not be required to change its transfer agent if its
current transfer agent cannot deliver Warrant Shares electronically through the
Depository Trust Corporation. A "DATE OF EXERCISE" means the date on which the
Holder shall have delivered to Company: (i) the Exercise Notice (with the
Warrant Exercise Log attached to it), appropriately completed and duly signed
and (ii) if such Holder is not utilizing the cashless exercise provisions set
forth in this Warrant, payment of the Exercise Price for the number of Warrant
Shares so indicated by the Holder to be purchased.

                  (b)      If by the third Trading Day after a Date of Exercise
the Company fails to deliver the required number of Warrant Shares in the manner
required pursuant to Section 5(a), then the Holder will have the right to
rescind such exercise.

                                      -2-

<PAGE>

                  (c)      If by the third Trading Day after a Date of Exercise
the Company fails to deliver the required number of Warrant Shares in the manner
required pursuant to Section 5(a), and if after such third Trading Day and prior
to the receipt of such Warrant Shares, the Holder purchases (in an open market
transaction or otherwise) shares of Common Stock to deliver in satisfaction of a
sale by the Holder of the Warrant Shares which the Holder anticipated receiving
upon such exercise (a "BUY-IN"), then the Company shall (1) pay in cash to the
Holder the amount by which (x) the Holder's total purchase price (including
brokerage commissions, if any) for the shares of Common Stock so purchased
exceeds (y) the amount obtained by multiplying (A) the number of shares of
Common Stock so purchased that the Company was required to deliver to the Holder
in connection with the exercise at issue for which such buy-in occurred by (B)
the closing bid price of the Common Stock at the time of the obligation giving
rise to such purchase obligation and (2) at the option of the Holder, either
reinstate the portion of the Warrant and equivalent number of Warrant Shares for
which such exercise was not honored or deliver to the Holder the number of
shares of Common Stock that would have been issued had the Company timely
complied with its exercise and delivery obligations hereunder. The Holder shall
provide the Company written notice indicating the amounts payable to the Holder
in respect of the Buy-In.

                  (d)      The Company's obligations to issue and deliver
Warrant Shares in accordance with the terms hereof are absolute and
unconditional, irrespective of any action or inaction by the Holder to enforce
the same, any waiver or consent with respect to any provision hereof, the
recovery of any judgment against any Person or any action to enforce the same,
or any setoff, counterclaim, recoupment, limitation or termination, or any
breach or alleged breach by the Holder or any other Person of any obligation to
the Company or any violation or alleged violation of law by the Holder or any
other Person, and irrespective of any other circumstance which might otherwise
limit such obligation of the Company to the Holder in connection with the
issuance of Warrant Shares. Nothing herein shall limit a Holder's right to
pursue any other remedies available to it hereunder, at law or in equity
including, without limitation, a decree of specific performance and/or
injunctive relief with respect to the Company's failure to timely deliver
certificates representing shares of Common Stock upon exercise of the Warrant as
required pursuant to the terms hereof.

         6.       Charges, Taxes and Expenses. Issuance and delivery of
certificates for shares of Common Stock upon exercise of this Warrant shall be
made without charge to the Holder for any issue or transfer tax, withholding
tax, transfer agent fee or other incidental tax or expense in respect of the
issuance of such certificates, all of which taxes and expenses shall be paid by
the Company; provided, however, that the Company shall not be required to pay
any tax which may be payable in respect of any transfer involved in the
registration of any certificates for Warrant Shares or Warrants in a name other
than that of the Holder. The Holder shall be responsible for all other tax
liability that may arise as a result of holding or transferring this Warrant or
receiving Warrant Shares upon exercise hereof.

         7.       Replacement of Warrant. If this Warrant is mutilated, lost,
stolen or destroyed, the Company shall issue or cause to be issued in exchange
and substitution for and upon cancellation hereof, or in lieu of and
substitution for this Warrant, a New Warrant, but only upon receipt of evidence
reasonably satisfactory to the Company of such loss, theft or destruction and
customary and reasonable indemnity (which shall not include a surety bond), if
requested.

                                      -3-

<PAGE>

Applicants for a New Warrant under such circumstances shall also comply with
such other reasonable regulations and procedures and pay such other reasonable
third-party costs as the Company may prescribe. If a New Warrant is requested as
a result of a mutilation of this Warrant, then the Holder shall deliver such
mutilated Warrant to the Company as a condition precedent to the Company's
obligation to issue the New Warrant.

         8.       Reservation of Warrant Shares. The Company covenants that it
will at all times reserve and keep available out of the aggregate of its
authorized but unissued and otherwise unreserved Common Stock, solely for the
purpose of enabling it to issue Warrant Shares upon exercise of this Warrant as
herein provided, the number of Warrant Shares which are then issuable and
deliverable upon the exercise of this entire Warrant, free from preemptive
rights or any other contingent purchase rights of persons other than the Holder
(taking into account the adjustments and restrictions of Section 9). The Company
covenants that all Warrant Shares so issuable and deliverable shall, upon
issuance and the payment of the applicable Exercise Price in accordance with the
terms hereof, be duly and validly authorized, issued and fully paid and
nonassessable.

         9.       Certain Adjustments. The Exercise Price and number of Warrant
Shares issuable upon exercise of this Warrant are subject to adjustment from
time to time as set forth in this Section 9.

                  (a)      Stock Dividends and Splits. If the Company, at any
time while this Warrant is outstanding, (i) pays a stock dividend on its Common
Stock or otherwise makes a distribution on any class of capital stock that is
payable in shares of Common Stock, (ii) subdivides outstanding shares of Common
Stock into a larger number of shares, or (iii) combines outstanding shares of
Common Stock into a smaller number of shares, then in each such case the
Exercise Price shall be multiplied by a fraction of which the numerator shall be
the number of shares of Common Stock outstanding immediately before such event
and of which the denominator shall be the number of shares of Common Stock
outstanding immediately after such event. Any adjustment made pursuant to clause
(i) of this paragraph shall become effective immediately after the record date
for the determination of stockholders entitled to receive such dividend or
distribution, and any adjustment pursuant to clause (ii) or (iii) of this
paragraph shall become effective immediately after the effective date of such
subdivision or combination. If any event requiring an adjustment under this
paragraph occurs during the period that an Exercise Price is calculated
hereunder, then the calculation of such Exercise Price shall be adjusted
appropriately to reflect such event.

                  (b)      Pro Rata Distributions. If the Company, at any time
while this Warrant is outstanding, distributes to all holders of Common Stock
(i) evidences of its indebtedness, (ii) any security (other than a distribution
of Common Stock covered by the preceding paragraph), (iii) rights or warrants to
subscribe for or purchase any security, or (iv) any other asset (in each case,
"DISTRIBUTED PROPERTY"), then, at the request of any Holder delivered before the
90th day after the record date fixed for determination of stockholders entitled
to receive such distribution, the Company will deliver to such Holder, within
five Trading Days after such request (or, if later, on the effective date of
such distribution), the Distributed Property that such Holder would have been
entitled to receive in respect of the Warrant Shares for which such Holder's
Warrant could have been exercised immediately prior to such record date. If such
Distributed Property is

                                      -4-

<PAGE>

not delivered to a Holder pursuant to the preceding sentence, then upon any
exercise of the Warrant that occurs after such record date, such Holder shall be
entitled to receive, in addition to the Warrant Shares otherwise issuable upon
such conversion, the Distributed Property that such Holder would have been
entitled to receive in respect of such number of Warrant Shares had the Holder
been the record holder of such Warrant Shares immediately prior to such record
date.

                  (c)      Fundamental Transactions. If, at any time while this
Warrant is outstanding, (1) the Company effects any merger or consolidation of
the Company with or into another Person, (2) the Company effects any sale of all
or substantially all of its assets in one or a series of related transactions,
(3) any tender offer or exchange offer (whether by the Company or another
Person) is completed pursuant to which holders of Common Stock are permitted to
tender or exchange their shares for other securities, cash or property, or (4)
the Company effects any reclassification of the Common Stock or any compulsory
share exchange pursuant to which the Common Stock is effectively converted into
or exchanged for other securities, cash or property (in any such case, a
"FUNDAMENTAL TRANSACTION"), then the Holder shall have the right thereafter to
receive, upon exercise of this Warrant, the same amount and kind of securities,
cash or property as it would have been entitled to receive upon the occurrence
of such Fundamental Transaction if it had been, immediately prior to such
Fundamental Transaction, the holder of the number of Warrant Shares then
issuable upon exercise in full of this Warrant (the "ALTERNATE CONSIDERATION").
For purposes of any such exercise, the determination of the Exercise Price shall
be appropriately adjusted to apply to such Alternate Consideration based on the
amount of Alternate Consideration issuable in respect of one share of Common
Stock in such Fundamental Transaction, and the Company shall apportion the
Exercise Price among the Alternate Consideration in a reasonable manner
reflecting the relative value of any different components of the Alternate
Consideration. If holders of Common Stock are given any choice as to the
securities, cash or property to be received in a Fundamental Transaction, then
the Holder shall be given the same choice as to the Alternate Consideration it
receives upon any exercise of this Warrant following such Fundamental
Transaction. At the Holder's request, any successor to the Company or surviving
entity in such Fundamental Transaction shall issue to the Holder a new warrant
substantially in the form of this Warrant and consistent with the foregoing
provisions and evidencing the Holder's right to purchase the Alternate
Consideration for the aggregate Exercise Price upon exercise thereof. The terms
of any agreement pursuant to which a Fundamental Transaction is effected shall
include terms requiring any such successor or surviving entity to comply with
the provisions of this paragraph (c) and insuring that the Warrant (or any such
replacement security) will be similarly adjusted upon any subsequent transaction
analogous to a Fundamental Transaction.

                  (d)      Number of Warrant Shares. Simultaneously with any
adjustment to the Exercise Price pursuant to paragraph (a) of this Section, the
number of Warrant Shares that may be purchased upon exercise of this Warrant
shall be increased or decreased proportionately, so that after such adjustment
the aggregate Exercise Price payable hereunder for the adjusted number of
Warrant Shares shall be the same as the aggregate Exercise Price in effect
immediately prior to such adjustment.

                  (e)      Calculations. All calculations under this Section 9
shall be made to the nearest cent or the nearest 1/100th of a share, as
applicable. The number of shares of Common Stock outstanding at any given time
shall not include shares owned or held by or for the account

                                      -5-

<PAGE>

of the Company, and the disposition of any such shares shall be considered an
issue or sale of Common Stock.

                  (f)      Notice of Adjustments. Upon the occurrence of each
adjustment pursuant to this Section 9, the Company at its expense will promptly
compute such adjustment in accordance with the terms of this Warrant and prepare
a certificate setting forth such adjustment, including a statement of the
adjusted Exercise Price and adjusted number or type of Warrant Shares or other
securities issuable upon exercise of this Warrant (as applicable), describing
the transactions giving rise to such adjustments and showing in detail the facts
upon which such adjustment is based. Upon written request, the Company will
promptly deliver a copy of each such certificate to the Holder and to the
Company's Transfer Agent.

                  (g)      Notice of Corporate Events. If the Company (i)
declares a dividend or any other distribution of cash, securities or other
property in respect of its Common Stock, including without limitation any
granting of rights or warrants to subscribe for or purchase any capital stock of
the Company or any Subsidiary, (ii) authorizes or approves, enters into any
agreement contemplating or solicits stockholder approval for any Fundamental
Transaction or (iii) authorizes the voluntary dissolution, liquidation or
winding up of the affairs of the Company, then the Company shall deliver to the
Holder a notice describing the material terms and conditions of such
transaction, at least 20 calendar days prior to the applicable record or
effective date on which a Person would need to hold Common Stock in order to
participate in or vote with respect to such transaction, and the Company will
take all steps reasonably necessary in order to insure that the Holder is given
the practical opportunity to exercise this Warrant prior to such time so as to
participate in or vote with respect to such transaction; provided, however, that
the failure to deliver such notice or any defect therein shall not affect the
validity of the corporate action required to be described in such notice.

         10.      Payment of Exercise Price. The Holder may pay the Exercise
Price in one of the following manners:

                  (a)      Cash Exercise. The Holder may deliver immediately
available funds; or

                  (b)      Cashless Exercise. If an Exercise Notice is delivered
after the Effectiveness Date (as defined in the Registration Rights Agreement
among the original Holder and the Company in connection with this Warrant) and a
registration statement permitting the Holder to resell the Warrant Shares is not
then effective or the prospectus forming a part thereof is not then available to
the Holder for the resale of the Warrant Shares, then the Holder may notify the
Company in an Exercise Notice of its election to utilize cashless exercise, in
which event the Company shall issue to the Holder the number of Warrant Shares
determined as follows:

                                X = Y [(A-B)/A]

                          where:

                                X = the number of Warrant Shares to be issued to
                                    the Holder.

                                      -6-

<PAGE>

                            Y = the number of Warrant Shares with respect to
                                which this Warrant is being exercised.

                            A = the average of the closing prices for the five
                                Trading Days immediately prior to (but not
                                including) the Exercise Date.

                            B = the Exercise Price.

For purposes of Rule 144 promulgated under the Securities Act, it is intended,
understood and acknowledged that the Warrant Shares issued in a cashless
exercise transaction shall be deemed to have been acquired by the Holder, and
the holding period for the Warrant Shares shall be deemed to have commenced, on
the date this Warrant was originally issued.

         11.      Limitation on Exercise. Notwithstanding anything to the
contrary contained herein, the number of shares of Common Stock that may be
acquired by the Holder upon any exercise of this Warrant (or otherwise in
respect hereof) shall be limited to the extent necessary to insure that,
following such exercise (or other issuance), the total number of shares of
Common Stock then beneficially owned by such Holder and its Affiliates and any
other Persons whose beneficial ownership of Common Stock would be aggregated
with the Holder's for purposes of Section 13(d) of the Exchange Act, does not
exceed 4.999% of the total number of issued and outstanding shares of Common
Stock (including for such purpose the shares of Common Stock issuable upon such
exercise). For such purposes, beneficial ownership shall be determined in
accordance with Section 13(d) of the Exchange Act and the rules and regulations
promulgated thereunder. Each delivery of an Exercise Notice hereunder will
constitute a representation by the Holder that it has evaluated the limitation
set forth in this paragraph and determined that issuance of the full number of
Warrant Shares requested in such Exercise Notice is permitted under this
paragraph. This provision shall not restrict the number of shares of Common
Stock which a Holder may receive or beneficially own in order to determine the
amount of securities or other consideration that such Holder may receive in the
event of a merger or other business combination or reclassification involving
the Company as contemplated in Section 9 of this Warrant. This restriction may
not be waived by a Holder.

         12.      No Fractional Shares. No fractional shares of Warrant Shares
will be issued in connection with any exercise of this Warrant. In lieu of any
fractional shares which would, otherwise be issuable, the Company shall pay cash
equal to the product of such fraction multiplied by the closing price of one
Warrant Share as reported on the Nasdaq National Market on the date of exercise.

         13.      Notices. Any and all notices or other communications or
deliveries hereunder (including, without limitation, any Exercise Notice) shall
be in writing and shall be deemed given and effective on the earliest of (i) the
date of transmission, if such notice or communication is delivered via facsimile
at the facsimile number specified in this Section prior to 6:30 p.m. (New York
City time) on a Trading Day, (ii) the next Trading Day after the date of
transmission, if such notice or communication is delivered via facsimile at the
facsimile number specified in this Section on a day that is not a Trading Day or
later than 6:30 p.m. (New York City time) on any Trading Day, (iii) the Trading
Day following the date of mailing, if sent by nationally recognized overnight
courier service, or (iv) upon actual receipt by the party to whom

                                      -7-

<PAGE>

such notice is required to be given. The addresses for such communications shall
be: (i) if to the Company, to Zix Corporation, 2711 North Haskell Avenue, Suite
2300 LB36, Dallas Texas 75204, Attn: Chief Financial Officer, Facsimile No.:
(214) 515-7390, or (ii) if to the Holder, to the address or facsimile number
appearing on the Warrant Register or such other address or facsimile number as
the Holder may provide to the Company in accordance with this Section.

         14.      Warrant Agent. The Company shall serve as warrant agent under
this Warrant. Upon 30 days' notice to the Holder, the Company may appoint a new
warrant agent. Any corporation into which the Company or any new warrant agent
may be merged or any corporation resulting from any consolidation to which the
Company or any new warrant agent shall be a party or any corporation to which
the Company or any new warrant agent transfers substantially all of its
corporate trust or shareholders services business shall be a successor warrant
agent under this Warrant without any further act. Any such successor warrant
agent shall promptly cause notice of its succession as warrant agent to be
mailed (by first class mail, postage prepaid) to the Holder at the Holder's last
address as shown on the Warrant Register.

         15.      Miscellaneous.

                  (a)      This Warrant shall be binding on and inure to the
benefit of the parties hereto and their respective successors and assigns.
Subject to the preceding sentence, nothing in this Warrant shall be construed to
give to any Person other than the Company and the Holder any legal or equitable
right, remedy or cause of action under this Warrant. This Warrant may be amended
only in writing signed by the Company and the Holder and their successors and
assigns.

                  (b)      All questions concerning the construction, validity,
enforcement and interpretation of this Warrant shall be governed by and
construed and enforced in accordance with the internal laws of the State of New
York, without regard to the principles of conflicts of law thereof. Each party
agrees that all legal proceedings concerning the interpretations, enforcement
and defense of this Warrant and the transactions herein contemplated
("PROCEEDINGS") (whether brought against a party hereto or its respective
Affiliates, employees or agents) shall be commenced exclusively in the state and
federal courts sitting in the City of New York, Borough of Manhattan (the "NEW
YORK COURTS"). Each party hereto hereby irrevocably submits to the exclusive
jurisdiction of the New York Courts for the adjudication of any dispute
hereunder or in connection herewith or with any transaction contemplated hereby
or discussed herein, and hereby irrevocably waives, and agrees not to assert in
any Proceeding, any claim that it is not personally subject to the jurisdiction
of any New York Court, or that such Proceeding has been commenced in an improper
or inconvenient forum. Each party hereto hereby irrevocably waives personal
service of process and consents to process being served in any such Proceeding
by mailing a copy thereof via registered or certified mail or overnight delivery
(with evidence of delivery) to such party at the address in effect for notices
to it under this Warrant and agrees that such service shall constitute good and
sufficient service of process and notice thereof. Nothing contained herein shall
be deemed to limit in any way any right to serve process in any manner permitted
by law. Each party hereto hereby irrevocably waives, to the fullest extent
permitted by applicable law, any and all right to trial by jury in any legal
proceeding arising out of or relating to this Warrant or the transactions
contemplated hereby. If either party shall commence a Proceeding to enforce any
provisions of this Warrant, then the

                                      -8-

<PAGE>

prevailing party in such Proceeding shall be reimbursed by the other party for
its attorney's fees and other costs and expenses incurred with the
investigation, preparation and prosecution of such Proceeding.

                  (c)      The headings herein are for convenience only, do not
constitute a part of this Warrant and shall not be deemed to limit or affect any
of the provisions hereof.

                  (d)      In case any one or more of the provisions of this
Warrant shall be invalid or unenforceable in any respect, the validity and
enforceability of the remaining terms and provisions of this Warrant shall not
in any way be affected or impaired thereby and the parties will attempt in good
faith to agree upon a valid and enforceable provision which shall be a
commercially reasonable substitute therefor, and upon so agreeing, shall
incorporate such substitute provision in this Warrant.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK,
                             SIGNATURE PAGE FOLLOWS]

                                      -9-

<PAGE>

         IN WITNESS WHEREOF, the Company has caused this Warrant to be duly
executed by its authorized officer as of the date first indicated above.

                                    ZIX CORPORATION

                                    By:
                                           -------------------------------------
                                    Name:
                                    Title:

<PAGE>

                                 EXERCISE NOTICE

To Zix Corporation:

         The undersigned hereby irrevocably elects to purchase _____________
shares of common stock, par value $.01 per share, of Zix Corporation ("COMMON
STOCK"), pursuant to Warrant No. [ ], originally issued June 24, 2003 (the
"WARRANT"), and, if such Holder is not utilizing the cashless exercise
provisions set forth in the Warrant, encloses herewith $________ in cash,
certified or official bank check or checks or other immediately available funds,
which sum represents the aggregate Exercise Price (as defined in the Warrant)
for the number of shares of Common Stock to which this Exercise Notice relates,
together with any applicable taxes payable by the undersigned pursuant to the
Warrant.

         By its delivery of this Exercise Notice, the undersigned represents and
warrants to the Company that in giving effect to the exercise evidenced hereby
the Holder will not beneficially own in excess of the number of shares of Common
Stock (determined in accordance with Section 13(d) of the Securities Exchange
Act of 1934) permitted to be owned under Section 11 of this Warrant to which
this notice relates.

         The undersigned requests that certificates for the shares of Common
Stock issuable upon this exercise be issued in the name of

                                                PLEASE INSERT SOCIAL SECURITY OR
                                                TAX IDENTIFICATION NUMBER

                         (Please print name and address)

<PAGE>

                           Warrant Shares Exercise Log

<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------
                                                                                Number of
                  Number of Warrant                                             Warrant Shares
                  Shares Available to be     Number of Warrant Shares           Remaining to
Date              Exercised                  Exercised                          be Exercised
----------------------------------------------------------------------------------------------
<S>               <C>                        <C>                                <C>

----------------------------------------------------------------------------------------------
</TABLE>

<PAGE>

                               FORM OF ASSIGNMENT

         [To be completed and signed only upon transfer of Warrant]

         FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers
unto ________________________________ the right represented by the within
Warrant to purchase ____________ shares of Common Stock of Zix Corporation to
which the within Warrant relates and appoints ________________ attorney to
transfer said right on the books of Zix Corporation with full power of
substitution in the premises.

Dated: _______________, ____

                            ____________________________________________________
                            (Signature must conform in all respects to name of
                            holder as specified on the face of the Warrant)

                            ____________________________________________________
                            Address of Transferee

                            ____________________________________________________

                            ____________________________________________________

In the presence of:

__________________________