<PAGE>
                                                                     EXHIBIT 4.2

                                ZIXIT CORPORATION
                             STOCK OPTION AGREEMENT

         THIS STOCK OPTION AGREEMENT (this "Agreement") is made and entered into
as of the 14th day of November 2001 by and between ZixIt Corporation, a Texas
corporation (the "Company"), and John Ryan ("Optionee").

         WHEREAS, the Company desires to employ Optionee as Chairman, Chief
Executive Officer and President of the Company, and Optionee desires to be
employed by the Company in such capacities pursuant to an Employment Agreement,
dated as of November 14, 2001 (the "Employment Agreement");

         WHEREAS, pursuant to the terms of the Employment Agreement, the Company
has agreed to grant stock options to Optionee to purchase 1,000,000 shares of
the Common Stock, par value $.01 per share of the Company (the "Common Stock");

         NOW, THEREFORE, the parties intending to be legally bound, agree as
follows:

1. OPTION GRANT. In consideration of the mutual agreements and covenants
contained herein and in the Employment Agreement, the Company hereby grants to
the Optionee, on the terms and conditions and subject to the restrictions as set
forth in this Agreement, a non-qualified stock option ("Option") to purchase
1,000,000 shares of Common Stock at a price per share (the "Option Price") equal
to the lower of: (i) $6.50 per share or (ii) the lowest two-consecutive-day
average closing price of Common Stock on the Nasdaq National Market System
during the 20 consecutive trading days following the Effective Date.

2. DEFINITIONS.

         a. Acquiring Person. An "Acquiring Person" shall mean any person
(including any "person" as such term is used in Sections 13 (d) (3) or 14 (d)
(2) of the Exchange Act) that, together with all Affiliates and Associates of
such person, is the beneficial owner of 30% or more of the outstanding Common
Stock. The term "Acquiring Person" shall not include the Company, any subsidiary
of the Company, any employee benefit plan of the Company (or trust with respect
thereto) or subsidiary of the Company, or any person holding Common Stock of the
Company for or pursuant to the terms of any such plan. For the purposes of this
Agreement, a person who becomes an Acquiring Person by acquiring beneficial
ownership of 30% or more of the Common Stock at any time after the date of this
Agreement shall continue to be an Acquiring Person whether or not such person
continues to be the beneficial owner of 30% or more of the outstanding Common
Stock.

         b. Affiliate and Associate. "Affiliate" and "Associate" shall have the
respective meanings ascribed to such terms in Rule 12b-2 of the General Rules
and Regulations under the Exchange Act in effect on the date of this Agreement.



----------
* Indicates confidential text omitted and filed separately with the Securities
and Exchange Commission.



                                  -Exhibit 4.2-
                                        1
<PAGE>

         c. Board. "Board" shall mean the Board of Directors of the Company.

         d. Cause. "Cause" shall have the meaning given such term in the
Employment Agreement.

         e. Change in Control. A "Change in Control" of the Company shall have
occurred if at any time during the term of this Agreement any of the following
events shall occur:

                  (i) Any Sale of the Company or any Material Subsidiary; or

                  (ii) Any Acquiring Person has become the beneficial owner of
         securities which, when added to any securities already owned by such
         person, would represent in the aggregate 30% or more of the
         then-outstanding securities of the Company that are entitled to vote to
         elect any class of directors; *; or

                  (iii) *; or

                  (iv) If, at any time, the Continuing Directors then serving on
         the Board cease for any reason to constitute at least a majority
         thereof; or

                  (v) Any occurrence that would be required to be reported in
         response to Item 6(e) of Schedule 14A of Regulation 14A or any
         successor rule or regulation promulgated under the Exchange Act.

         f. Continuing Director. A "Continuing Director" shall mean a director
of the Company who (i) is not an Acquiring Person or an Affiliate or Associate
thereof, or a representative of an Acquiring Person or nominated for election by
an Acquiring Person, and (ii) was either a member of the Board on the date of
this Agreement or subsequently became a director of the Company and whose
initial election or initial nomination for election by the Company's
shareholders was approved by a majority of the Continuing Directors then on the
Board.

         g. Disability. "Disability" shall have the meaning given such term in
the Employment Agreement.

         h. Effective Date. "Effective Date" shall have the meaning given such
term in the Employment Agreement.

         i. Exchange Act. "Exchange Act" shall mean the Securities Exchange Act
of 1934, as amended, and the rules and regulations promulgated thereunder.



                                  -Exhibit 4.2-
                                        2
<PAGE>

         j. Fair Market Value. "Fair Market Value" shall mean the closing sale
price (or average of the quoted closing bid and asked prices if there is no
closing sale price reported) of the Common Stock on the date specified as
reported by the Nasdaq National Market, or by the principal national stock
exchange on which the Common Stock is then listed. If there is no reported price
information for such date, the Fair Market Value will be determined by the
reported price information for Common Stock on the day nearest preceding such
date.

         k. Good Reason. "Good Reason" shall have the meaning given such term in
the Employment Agreement.

         l. Material Subsidiary. A "Material Subsidiary" shall mean any
majority-owned subsidiary of the Company that is material to the business of the
Company, taken as a whole.

         m. *.

         n. Person. A "Person" shall mean an individual, a corporation, a
partnership, an association, a joint-stock company, a trust, an incorporated
organization, or a government or political subdivision thereof and any other
entity. A Person, together with that Person's Affiliates and Associates, and any
Persons acting as a partnership, limited partnership, joint venture,
association, syndicate, or other group (whether or not formally organized), or
otherwise acting jointly or in concert or in a coordinated or consciously
parallel manner (whether or not pursuant to any express agreement), for the
purpose of acquiring, holding, voting, or disposing of securities of the Company
with that Person, shall be deemed a single "Person."

         o. Resignation. "Resignation" shall mean the voluntary termination by
Optionee of his employment relationship with the Company under circumstances
other than voluntary Retirement or resignation for Good Reason.

         p. Retirement. "Retirement" shall mean the termination of Optionee's
employment in accordance with the requirements of a written retirement plan,
policy or rule of the Company that has been duly adopted by the Company or
employing Material Subsidiary, as applicable.

         q. Sale. A "Sale" occurs with respect to the Company or a Material
Subsidiary, as applicable, if it engages in a merger, consolidation,
recapitalization, reorganization, or sale, lease, license, transfer, or other
effective disposition of all or substantially all of the Company's or Material
Subsidiary's assets and the Company or its shareholders or Affiliates
immediately before such transaction beneficially own, immediately after or as a
result of such transaction, equity securities of the surviving or acquiring
corporation or such corporation's parent corporation possessing less than 51% of
the voting power of the surviving or acquiring Person or such Person's parent
corporation, provided that a Sale shall not be deemed to occur upon any public
offering or series of such offerings of securities of the Company or a Material
Subsidiary that results in any such change in beneficial ownership.

         r. Securities Act. "Securities Act" shall mean the Securities Act of
1933, as amended, and the rules and regulations promulgated thereunder.



                                  -Exhibit 4.2-
                                        3
<PAGE>

3. TERM OF OPTION AND VESTING.

         a. The term of this Option shall expire, and shall not be exercisable
with respect to any vested shares of Common Stock hereunder as to which the
Option has not been exercised, on the tenth anniversary of the date hereof (the
"stated term"), except as such stated term may be otherwise shortened by the
other provisions set forth in Paragraph 5 below. Except as otherwise provided in
subparagraph (b) below, the Option shall vest in increments as follows:

<Table>
<Caption>
                              Date                                                   Percent Vested
                              ----                                                   --------------
<S>                                                                                  <C>
         First anniversary of Effective Date                                                50%
         90 days after first anniversary of Effective Date                                62.5%
         180 days after first anniversary of Effective Date                               75.0%
         270 days after first anniversary of Effective Date                               87.5%
         Second anniversary of Effective Date                                            100.0%
</Table>

         b. Upon the earliest to occur of: (i) a Change in Control; (ii) the
Optionee's employment with the Company or Material Subsidiary is terminated
without Cause; or (iii) Optionee terminates his employment with the Company or
Material Subsidiary for Good Reason (such three events each being an
"Accelerated Vesting Event"), the Option shall immediately vest in full and
remain exercisable for a period of (a) two years as to all shares of Common
Stock subject thereto with respect to the occurrence of an event referred to in
(i) or (iii) above, or (b) six months as to all shares of Common Stock subject
thereto with respect to the occurrence of an event referred to in (ii) above.

4. EXERCISE OF OPTION.

         a. The Option shall be exercisable only with respect to vested shares
of Common Stock subject thereto and subject to Paragraph 5 below, shall not be
exercisable with respect to any vested shares of Common Stock unless Optionee
shall, at the time of exercise, be an employee, consultant or director of the
Company or a Material Subsidiary, except as covered in Paragraph 3(b) above or
Paragraph 5 below. However, this Option may not be exercised as to less than 100
vested shares at any one time (or the remaining shares then purchasable under
this Option, if less than 100 shares).


         b. This Option may be exercised with respect to any vested shares of
Common Stock only by written notice (the "Exercise Notice") by Optionee to the
Company at its principal executive office to the attention of the Company's
chief financial officer. The Exercise Notice shall be deemed given when
deposited in the U. S. mails, postage prepaid, addressed to the Company at its
principal executive office, or if given other than by deposit in the U.S. mails,
when delivered in person to an executive officer of the Company at that office.
The date of exercise of this Option shall be the date of the postmark if the
notice is mailed or the date received if the notice is delivered other than by
mail. The Exercise Notice shall state the number of shares in respect of which
this Option is being exercised and, if the shares for which this Option is being
exercised are to be evidenced by more than one stock certificate, the
denominations in which the stock certificates are to be issued. The Exercise
Notice shall be



                                  -Exhibit 4.2-
                                        4
<PAGE>

signed by Optionee and shall include his complete address, together with his
social security number.

         c. This Option may be exercised either by tendering cash in the amount
of the Option Price or, with the Company's consent, such consent to be given by
the Compensation and Stock Option Committee of the Board, subject to compliance
with applicable requirements of Section 16(b) under the Exchange Act, by
tendering shares of Common Stock. The Exercise Notice shall be accompanied by
payment of the aggregate Option Price of the shares purchased by cash, a
certified cashier's check or, at the Company's option, by delivery of shares of
Common Stock having a Fair Market Value on the date immediately preceding the
exercise date equal to the Option Price. The Exercise Notice shall also be
accompanied by payment of the amount that the Company is required to withhold
for federal income or other tax purposes (unless the Optionee has provided for
payment of those taxes to the Company in another manner permitted under this
Agreement). If the Option is exercised in full or in part, the Optionee shall
surrender this Agreement to the Company so that the Company may make appropriate
notation hereon or cancel this Agreement and issue a new agreement representing
the unexercised portion of the Option.

         d. If the shares of Common Stock issued upon the exercise of the Option
are covered by an effective registration statement under the Securities Act, the
Option may be exercised by a broker-dealer acting on behalf of the Optionee if
(i) the broker-dealer has received from the Optionee or the Company a fully- and
duly-endorsed agreement evidencing the Option, together with instructions signed
by the Optionee requesting the Company to deliver the shares of Common Stock
subject to the Option to the broker-dealer on behalf of the Optionee and
specifying the account into which such shares should be deposited, (ii) adequate
provision has been made with respect to the payment of any withholding taxes due
upon such exercise, (iii) the broker-dealer delivers to the Company the
aggregate Option Price in accordance with the paragraph above, and (iv) the
broker-dealer and the Optionee have otherwise complied with Section 220.3(e)(4)
of Regulation T, 12 CFR Part 220, or any successor provision.

         e. The certificates for shares of Common Stock as to which this Option
shall have been so exercised shall be registered in the name of the Optionee and
shall be delivered to the Optionee at the address specified in the Exercise
Notice. An option exercise shall be valid only if the Optionee makes payment or
other arrangements relating to the withholding tax obligations discussed in
Paragraph 9. In the event the person exercising this Option is a transferee of
the Optionee by will or under the laws of descent and distribution, the Exercise
Notice shall be accompanied by appropriate proof of the right of such transferee
to exercise this Option.

         f. This Option is not transferable otherwise than by will or the laws
of descent and distribution, and is exercisable during the Optionee's lifetime
only by Optionee. Without limiting the generality of the foregoing, this Option
may not be assigned, transferred (except as aforesaid), pledged or hypothecated
in any way (whether by operation of law or otherwise), and shall not be subject
to execution, attachment, or similar process, without the prior written consent
of the Company. Any attempted assignment, transfer, pledge, or hypothecation
contrary to the provisions hereof shall be void and ineffective for all
purposes.



                                  -Exhibit 4.2-
                                        5
<PAGE>

5. TERMINATION OF OPTION.

         a. In the event Optionee ceases to be an employee, consultant or
director of either the Company or a Material Subsidiary due to death,
Retirement, Resignation, Disability or termination by the Company for any reason
other than Cause (such five events each being a "Qualified Termination"), this
Option may be exercised with respect to vested shares by the Optionee or his
estate, personal representative or beneficiary to the fullest extent that
Optionee was entitled to exercise the same on the day immediately prior to such
termination (i) at any time within the one-year period commencing on the day
next following such termination if such termination is due to the death of the
Optionee; (ii) at any time within the 30-day period commencing on the day next
following the effective date of such termination if such termination is due to
the Resignation of the Optionee; or (iii) at any time within the six-month
period commencing on the day next following such termination in the case of any
other Qualified Termination (or in any such case in (i), (ii) or (iii) above, if
shorter, only for the remaining stated term of this Option). In the event that
the Optionee's employment is terminated for any reason other than a Qualified
Termination, this Option shall automatically expire simultaneously with such
termination. Notwithstanding the preceding provisions of this Paragraph,
following any Accelerated Vesting Event, this Option shall remain exercisable
for the period set forth in Paragraph 3(b).

         b. After the Optionee's death, this Option shall be exercisable only by
the executor or administrator of the Optionee's estate, or if the Optionee's
estate is not in administration, by the person or persons to whom the Optionee's
rights shall have passed by the Optionee's will or under the laws of descent and
distribution of the state where the Optionee was domiciled at the date of death.

6. RIGHTS AS SHAREHOLDER. Neither the Optionee nor any person claiming under or
through the Optionee shall be or have any rights or privileges of a shareholder
of the Company in respect of any of the shares of Common Stock issuable upon the
exercise of this Option, unless and until certificates representing such shares
of Common Stock shall have been issued (as evidenced by the appropriate entry on
the books of the Company or of a duly authorized transfer agent of the Company).

7. STATE AND FEDERAL SECURITIES REGULATION.

         a. The shares of Common covered by the Option have not been registered
under the Securities Act or qualified under applicable state securities laws.
The Company agrees to include the shares of Common Stock covered by the Option
on a registration statement on Form S-8 within 60 days after the date of this
Agreement and to use commercially reasonable efforts to maintain the
effectiveness of such registration statement during the term of this Agreement
and any period during which this Option is exercisable, subject to the following
provisions related to the Company's ability to temporarily suspend the
effectiveness of such registration statement.

         b. No shares of Common Stock covered by this Option shall be issued by
the Company upon the exercise of this Option unless and until any
then-applicable requirements of state and federal laws and regulatory agencies
shall have been fully complied with to the



                                  -Exhibit 4.2-
                                        6
<PAGE>

satisfaction of the Company and its counsel. The Company may suspend for a
reasonable period or periods the time during which this Option may be exercised
if, in the opinion of the Company, such suspension is required to enable the
Company to remain in compliance with regulatory requirements relating to the
issuance of shares of Common Stock subject to this Option. This Option is
subject to the requirement that, if at any time the Company shall determine, in
its discretion, that the listing, registration or qualification of the shares of
Common Stock subject to this Option upon any securities exchange or under any
state or federal law, or the consent or approval of any government regulatory
body, is necessary or desirable as a condition of, or in connection with, the
granting or exercise of this Option or the issue or purchase of shares under
this Option, this Option may not be exercised in whole or in part until such
listing, registration, qualification, consent or approval shall have been
effected or obtained free of any conditions not acceptable to the Company. The
Company shall be under no obligation to effect or obtain any such listing,
registration, qualification, consent or approval if the Company shall determine,
in its discretion, that such action would not be in the best interest of the
Company. The Company shall not be liable for damages due to a delay in the
delivery or issuance of any stock certificates for any reason whatsoever,
including, but not limited to, a delay caused by listing, registration or
qualification of the shares of Common Stock subject to an option upon any
securities exchange or under any federal or state law or the effecting or
obtaining of any consent or approval of any governmental body with respect to
the granting or exercise of this Option or the issue or purchase of shares under
this Option. At the Company's election, the certificate evidencing shares of
Common Stock issued to the Optionee may be legended as follows, if necessary:

         THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
         UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR UNDER THE APPLICABLE
         SECURITIES LAWS OF ANY STATE OR OTHER JURISDICTION AND MAY NOT BE
         OFFERED FOR SALE, SOLD, ASSIGNED, TRANSFERRED, PLEDGED, OR OTHERWISE
         DISPOSED OF EXCEPT IN COMPLIANCE WITH THE REQUIREMENTS OF SUCH ACT AND
         THE APPLICABLE SECURITIES LAWS OF ANY STATE OR OTHER JURISDICTION.

Also, if applicable, a legend evidencing any transfer restrictions imposed by
this Agreement may also, at the Company's election, be affixed to the shares of
Common Stock issued to the Optionee.

8. ADJUSTMENT. If there is any change in the number or class of shares of Common
Stock through the declaration of stock or cash dividends, or recapitalization
resulting in stock splits, or combinations or exchanges of such shares, the
number or class of shares subject to the Option and/or the Option Price may be
proportionately adjusted by the Board in its sole discretion to reflect any such
change in the number or class of issued shares of Common Stock; provided,
however, that any fractional shares resulting from any such adjustment shall be
eliminated. In the event of any other extraordinary corporate transaction,
including but not limited to, distributions of cash or other property to the
Company's shareholders, the Board may equitably adjust the shares subject to the
Option and/or the Option Price as it deems appropriate in its sole discretion.



                                  -Exhibit 4.2-
                                        7
<PAGE>

9. WITHHOLDING OF TAXES. The Company may make such provisions and take such
steps as it may deem necessary or appropriate for the withholding of any taxes
which the Company or any subsidiary is required by any law or regulation of any
governmental authority, whether federal, state or local, domestic or foreign, to
withhold in connection with the withholding of the issuance of all or any
portion of the shares of Common Stock subject to this Option until the Optionee
reimburses the Company or the applicable subsidiary for the amount the Company
or the applicable subsidiary is required to withhold with respect to such taxes,
subject to compliance with applicable requirements of Section 16(b) under the
Exchange Act, canceling, retaining or withholding any portion of such shares of
Common Stock in an amount sufficient to reimburse the Company or the applicable
subsidiary for the minimum amount it is required to so withhold, or taking any
other action reasonably required to satisfy the minimum withholding obligation
of the Company or the applicable subsidiary.

10. CONTINUED EMPLOYMENT NOT PRESUMED. Nothing in this Agreement or any document
describing it nor the grant of the Option shall give the Optionee the right to
continue in employment with the Company or any of its Subsidiaries or affect the
right of the Company to terminate the employment of the Optionee with or without
Cause.

11. NO LIABILITY OF OPTION. This Option is not liable for or subject to, in
whole or in part, the debts, contracts, liabilities or torts of the Optionee nor
shall it be subject to garnishment, attachment, execution, levy or other legal
or equitable process.

12. GOVERNING LAW. The interpretation, performance and enforcement of this
Agreement shall be governed by and construed in accordance with the laws of the
State of Texas and the United States, as applicable, without reference to the
conflict of laws rules thereof.

13. ENTIRE AGREEMENT. This Agreement and the Employment Agreement constitute the
entire agreement between the parties pertaining to the subject matter hereof and
supersede all prior and contemporaneous agreements, representations and
understandings of the parties. No supplement, modification or amendment of this
Agreement shall be binding unless executed in writing by the party to be charged
therewith. No waiver of any of the provisions of this Agreement shall be deemed,
or shall constitute a waiver of any other provision, whether or not similar, nor
shall any waiver constitute a continuing waiver.

14. DUPLICATE ORIGINALS. Duplicate originals of this document shall be executed
by both the Company and the Optionee, each of which shall retain one duplicate
original.

15. NOTICE. Other than any Exercise Notice, any notice required or permitted to
be given under this Agreement shall be in writing and delivered in person or
sent by registered or certified mail, return receipt requested, first-class
postage prepaid, (i) if to the Optionee, at the address shown on the books and
records of the Company, or (ii) if to the Company, at 2711 N. Haskell Avenue,
Suite 2850, LB 36, Dallas, Texas 75204-2911: Attention: Treasurer, or any other
address that may be given by either party to the other party by notice pursuant
to this Paragraph. Any notice other than any Exercise Notice, if sent by
registered or certified mail, shall be deemed to have been given when received.



                                  -Exhibit 4.2-
                                        8
<PAGE>

16. MISCELLANEOUS.

         a. If any provision of this Agreement is declared or found to be
illegal, unenforceable or void, in whole or in part, then the parties shall be
relieved of all obligations arising under such provision, but only to the extent
that it is illegal, unenforceable, or void, it being the intent and agreement of
the parties that this Agreement shall be deemed amended by modifying such
provision to the extent necessary to make it legal and enforceable while
preserving its intent or, if that is not possible, by substituting therefor
another provision that is legal and enforceable and achieves the same
objectives.

         b. All section titles and captions in this Agreement are for
convenience only, shall not be deemed part of this Agreement, and in no way
shall define, limit, extend, or describe the scope or intent of any provisions
of this Agreement.

         c. No failure by any party to insist upon the strict performance of any
covenant, duty, agreement or condition of this Agreement or to exercise any
right or remedy consequent upon a breach thereof shall constitute waiver of any
such breach or any other covenant, duty, agreement, or condition.

                                       THE COMPANY:

                                       ZIXIT CORPORATION


                                       By /s/ David P. Cook
                                         ---------------------------------------
                                         David P. Cook, CEO


                                       OPTIONEE:


                                       By /s/ John Ryan
                                         ---------------------------------------
                                         John Ryan



                                  -Exhibit 4.2-
                                        9