Document:

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                                                                     EXHIBIT 4.2
                                                                  EXECUTION COPY

                          REGISTRATION RIGHTS AGREEMENT

         REGISTRATION RIGHTS AGREEMENT (this "AGREEMENT"), dated as of July 22,
2003, by and between Zix Corporation, a Texas corporation, with its headquarters
located at 2711 North Haskell Avenue, Suite 2300 LB36, Dallas, Texas 75204 (the
"COMPANY"), and PocketScript L.L.C., an Ohio limited liability company (the
"SELLING SHAREHOLDER").

         WHEREAS:

         A.       In connection with an Asset Purchase Agreement between the
parties dated of even date herewith (the "ASSET PURCHASE AGREEMENT"), the
Company has agreed, upon the terms and subject to the conditions contained
therein, to issue and sell to the Selling Shareholder the shares of its Common
Stock, par value $.01 per share (the "COMMON STOCK") referenced in Section 4.1
of the Asset Purchase Agreement; and

         B.       To induce the Selling Shareholder to execute and deliver the
Asset Purchase Agreement, the Company has agreed to provide certain registration
rights under the Securities Act of 1933, as amended, and the rules and
regulations thereunder, or any similar successor statute (collectively, the
"1933 ACT"), and applicable state securities laws;

         NOW, THEREFORE, in consideration of the premises and the mutual
covenants contained herein and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the Company and the
Selling Shareholder hereby agrees as follows:

                                    ARTICLE I.
                                   DEFINITIONS

         Section 1.1. As used in this Agreement, the following terms shall have
the following meanings:

                  (a)      "SELLING SHAREHOLDER" means the Selling Shareholder.

                  (b)      "REGISTER," "REGISTERED," and "REGISTRATION" refer to
         a registration effected by preparing and filing a Registration
         Statement or Statements in compliance with the 1933 Act and pursuant to
         Rule 415 under the 1933 Act or any successor rule providing for
         offering securities on a continuous basis ("RULE 415"), and the
         declaration or ordering of effectiveness of such Registration Statement
         by the United States Securities and Exchange Commission (the "SEC").

                  (c)      "REGISTRABLE SECURITIES" means shares of Common Stock
         being issued to the Selling Shareholder pursuant to the Asset Purchase
         Agreement.

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                  (d)      "REGISTRATION STATEMENT(s)" means a registration
         statement(s) of the Company under the 1933 Act.

         Section 1.2. Capitalized terms used herein and not otherwise defined
herein shall have the respective meanings set forth in the Asset Purchase
Agreement.

                                   ARTICLE II.
                                  REGISTRATION

         Section 2.1.      REGISTRATION. The Company shall prepare, and, on or
prior to the date (the "FILING DATE") that is the later of (i) thirty (30)
calendar days after the Closing or (ii) two business days following the
effectiveness of that certain registration statement (the "Equity Financing
Registration Statement") to be filed with respect to the equity financing
completed by the Company in June 2003, as reported in the Company's Current
Report on Form 8-K dated June 25, 2003 and filed with Securities and Exchange
Commission, file with the SEC a Registration Statement on Form S-3 (or, if Form
S-3 is not then available, on such form of Registration Statement as is then
available to effect a registration of the Registrable Securities, subject to the
consent of the Selling Shareholder, which consent will not be unreasonably
withheld, conditioned or delayed) covering the resale of the Registrable
Securities. The Company shall provide a draft of the Registration Statement to
counsel for the Selling Shareholder prior to its filing or other submission so
that such counsel has a reasonable opportunity to review and comment on the
Registration Statement prior to it being filed. The Company shall use all
commercially reasonable efforts to obtain effectiveness of the Registration
Statement as soon as possible thereafter. The Company shall file the Equity
Financing Registration Statement on or before July 24, 2003, and shall use
commercially reasonable efforts to cause it to become effective as soon as
practicable. Except as set forth in Schedule 2.1 attached hereto, the Company
agrees not to file any other registration statement on Form S-3 until the
Registration Statement to be filed by the Company for the benefit of the Selling
Shareholder becomes effective. If the Company should breach this obligation,
then the Selling Shareholder shall have the remedies provided for in Article X.

         Section 2.2.      UNDERWRITTEN OFFERING. If any offering pursuant
to a Registration Statement pursuant to Section 2.1 hereof involves an
underwritten offering, the Selling Shareholder shall have the right to select
one legal counsel and the right to select the investment banker or bankers and
manager or managers to administer the offering (subject to the approval of the
Company, which approval shall not be unreasonably withheld, conditioned or
delayed). In the event that the Selling Shareholder elects not to participate in
such underwritten offering, the Registration Statement covering all of the
Registrable Securities shall contain appropriate plans of distribution
reasonably satisfactory to the Selling Shareholder.

         Section 2.3.      ELIGIBILITY FOR FORM S-3. The Company represents and
warrants that, to the best of its knowledge, it meets the registrant eligibility
and transaction requirements for the use of Form S-3 for registration of the
sale by the Selling Shareholder and the Company shall file all reports required
to be filed by the Company with the SEC in a timely manner so as to maintain
such eligibility for the use of Form S-3.

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                                  ARTICLE III.
                           OBLIGATIONS OF THE COMPANY

         In connection with the registration of the Registrable Securities, the
Company shall have the following obligations:

         Section 3.1.      The Company shall prepare promptly, and file with the
SEC as soon as practicable after the Closing (but in no event later than the
Filing Date), a Registration Statement with respect to the number of Registrable
Securities provided in Section 2.1, and thereafter use its commercially
reasonable efforts to cause such Registration Statement relating to Registrable
Securities to become effective as soon as possible after such filing, and keep
the Registration Statement effective pursuant to Rule 415 at all times until
such date as is the earlier of (i) the date on which all of the Registrable
Securities have been sold and (ii) the date on which the Registrable Securities
(in the opinion of Company's counsel) may be immediately sold to the public
without registration or restriction (including without limitation as to volume
by each holder thereof) under the 1933 Act (the "REGISTRATION PERIOD"), which
Registration Statement (including any amendments or supplements thereto and
prospectuses contained therein) shall not contain any untrue statement of a
material fact or omit to state a material fact required to be stated therein, or
necessary to make the statements therein not misleading.

         Section 3.2.      The Company shall prepare and file with the SEC such
amendments (including post-effective amendments) and supplements to the
Registration Statements and the prospectus used in connection with the
Registration Statements as may be necessary to keep the Registration Statements
effective at all times during the Registration Period, and, during such period,
comply with the provisions of the 1933 Act with respect to the disposition of
all Registrable Securities of the Company covered by the Registration
Statements, including any amendments that may be required to allow the permitted
assignees of Seller (as set forth in Section 10.6) to sell Registrable
Securities under the Registration Statements.

         Section 3.3.      The Company shall furnish to each Selling Shareholder
whose Registrable Securities are included in a Registration Statement and its
legal counsel (i) promptly after the same is prepared and publicly distributed,
filed with the SEC, or received by the Company, one copy of each Registration
Statement and any amendment thereto, each preliminary prospectus and prospectus
and each amendment or supplement thereto, and (ii) such number of copies of a
prospectus, including a preliminary prospectus, and all amendments and
supplements thereto and such other documents as such Selling Shareholder may
reasonably request in order to facilitate the disposition of the Registrable
Securities owned by such Selling Shareholder. The Company will immediately
notify each Selling Shareholder of the effectiveness of each Registration
Statement or any post-effective amendment. The Company will promptly respond to
any and all comments received from the SEC, with a view towards causing each
Registration Statement or any amendment thereto to be declared effective by the
SEC as soon as practicable and shall file an acceleration request as soon as
practicable following the resolution or clearance of all SEC comments or, if
applicable, following notification by the SEC that any such Registration
Statement or any amendment thereto will not be subject to review.

         Section 3.4.      The Company shall use reasonable efforts to (i)
register and qualify the Registrable Securities covered by the Registration
Statements under such other securities or

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"BLUE SKY" laws of such jurisdictions in the United States as each Selling
Shareholder may reasonably request, if an exemption from such securities or blue
sky laws is not otherwise available, (ii) prepare and file in those
jurisdictions such amendments (including post-effective amendments) and
supplements to such registrations and qualifications as may be necessary to
maintain the effectiveness thereof during the Registration Period, (iii) take
such other actions as may be necessary to maintain such registrations and
qualifications in effect at all times during the Registration Period, and (iv)
take all other actions reasonably necessary or advisable to qualify the
Registrable Securities for sale in such jurisdictions; provided, however, that
the Company shall not be required in connection therewith or as a condition
thereto to (a) qualify to do business in any jurisdiction where it would not
otherwise be required to qualify but for this Section 3.4, (b) subject itself to
general taxation in any such jurisdiction, (c) file a general consent to service
of process in any such jurisdiction, or (d) make any change in its charter or
bylaws, which in each case the Board of Directors of the Company determines to
be contrary to the best interests of the Company and its shareholders.

         Section 3.5.      In the event the Selling Shareholder selects
underwriters for the offering, the Company shall enter into and perform its
obligations under an underwriting agreement, in usual and customary form,
including, without limitation, customary indemnification and contribution
obligations, with the underwriters of such offering.

         Section 3.6.      As promptly as practicable after becoming aware of
such event, the Company shall notify each Selling Shareholder of the happening
of any event, of which the Company has knowledge, as a result of which the
prospectus included in any Registration Statement, as then in effect, includes
an untrue statement of a material fact or omission to state a material fact
required to be stated therein or necessary to make the statements therein not
misleading, and use its commercially reasonable efforts promptly to prepare a
supplement or amendment to any Registration Statement to correct such untrue
statement or omission, and deliver such number of copies of such supplement or
amendment to each Selling Shareholder as such Selling Shareholder may reasonably
request; provided that, for not more than fifteen (15) consecutive trading days
(or a total of not more than thirty (30) trading days in any twelve (30) month
period), the Company may delay the disclosure of material non-public information
concerning the Company (as well as prospectus or Registration Statement
updating) the disclosure of which at the time is not, in the good faith opinion
of the Company, in the best interests of the Company (an "ALLOWED DELAY");
provided, further, that the Company shall promptly (i) notify the Selling
Shareholder in writing of the existence of (but in no event, without the prior
written consent of an Selling Shareholder, shall the Company disclose to such
Selling Shareholder any of the facts or circumstances regarding) material
non-public information giving rise to an Allowed Delay and (ii) advise the
Selling Shareholder in writing to cease all sales under such Registration
Statement until the end of the Allowed Delay. Upon expiration of the Allowed
Delay, the Company shall again be bound by the first sentence of this Section
3.6 with respect to the information giving rise thereto.

         Section 3.7.      The Company shall use its commercially reasonable
efforts to prevent the issuance of any stop order or other suspension of
effectiveness of any Registration Statement, and, if such an order is issued, to
obtain the withdrawal of such order at the earliest possible moment and to
notify each Selling Shareholder who holds Registrable Securities being sold (or,

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in the event of an underwritten offering, the managing underwriters) of the
issuance of such order and the resolution thereof.

         Section 3.8.      The Company shall permit a single firm of counsel
designated by the Selling Shareholder to review such Registration Statement, and
all amendments and supplements thereto (as well as all requests for acceleration
or effectiveness thereof (collectively, the "REGISTRATION DOCUMENTS")) a
reasonable period of time prior to their filing with the SEC, and not file (or
send) any Registration Documents in a form to which such counsel reasonably
objects and will not request acceleration of such Registration Statement without
prior notice to such counsel. The sections of such Registration Statement
covering information with respect to the Selling Shareholder, the Selling
Shareholder's beneficial ownership of securities of the Company or the Selling
Shareholder's intended method of disposition of Registrable Securities shall
conform to the information provided to the Company by the Selling Shareholder.

         Section 3.9.      The Company shall (i) cause all the Registrable
Securities covered by the Registration Statement to be listed on each national
securities exchange on which securities of the same class or series issued by
the Company are then listed, if any, if the listing of such Registrable
Securities is then permitted under the rules of such exchange, or (ii) to the
extent the securities of the same class or series are not then listed or
permitted to be listed on a national securities exchange, secure the designation
and quotation of all the Registrable Securities covered by the Registration
Statement on Nasdaq or, if not eligible for Nasdaq on the Nasdaq SmallCap.

         Section 3.10.     The Company shall provide a transfer agent and
registrar, which may be a single entity, for the Registrable Securities not
later than the effective date of the Registration Statement.

         Section 3.11.     At the request of the Selling Shareholder, the
Company shall prepare and file with the SEC such amendments (including
post-effective amendments) and supplements to a Registration Statement and any
prospectus used in connection with the Registration Statement as may be
necessary in order to change the plan of distribution set forth in such
Registration Statement.

         Section 3.12.     The Company shall not, and shall not agree to, allow
the holders of any securities of the Company to include any of their securities
in any Registration Statement under Section 2.1 hereof or any amendment or
supplement thereto under Section 3.2 hereof without the consent of the Selling
Shareholder. In addition, the Company shall not offer any securities for its own
account or the account of others in any Registration Statement under Section 2.1
hereof or any amendment or supplement thereto under Section 3.2 hereof without
the consent of the Selling Shareholder.

         Section 3.13.     The Company shall take all other reasonable actions
necessary to expedite and facilitate disposition by the Selling Shareholder of
Registrable Securities pursuant to a Registration Statement.

         Section 3.14.     The Company shall comply with all applicable laws
related to a Registration Statement and offering and sale of securities and all
applicable rules and regulations

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of governmental authorities in connection therewith (including without
limitation the 1933 Act and the 1934 Act (as defined below) and the rules and
regulations promulgated by the SEC).

                                  ARTICLE IV.
                     OBLIGATIONS OF THE SELLING SHAREHOLDER

         In connection with the registration of the Registrable Securities, the
Selling Shareholder shall have the following obligations:

         Section 4.1.      It shall be a condition precedent to the obligations
of the Company to complete the registration pursuant to this Agreement with
respect to the Registrable Securities of a particular Selling Shareholder that
such Selling Shareholder shall furnish to the Company such information regarding
itself, the Registrable Securities held by it and the intended method of
disposition of the Registrable Securities held by it as shall be reasonably
required to effect the registration of such Registrable Securities and shall
execute such documents in connection with such registration as the Company may
reasonably request. At least ten (10) days prior to the first anticipated filing
date of the Registration Statement, the Company shall notify each Selling
Shareholder of the information the Company requires from each such Selling
Shareholder.

         Section 4.2.      Each Selling Shareholder, by such Selling
Shareholder's acceptance of the Registrable Securities, agrees to cooperate with
the Company as reasonably requested by the Company in connection with the
preparation and filing of the Registration Statements hereunder, unless such
Selling Shareholder has notified the Company in writing of such Selling
Shareholder's election to exclude all of such Selling Shareholder's Registrable
Securities from the Registration Statements.

         Section 4.3.      If the services of an underwriter are engaged, each
Selling Shareholder agrees to enter into and perform such Selling Shareholder's
obligations under an underwriting agreement, in usual and customary form,
including, without limitation, customary indemnification and contribution
obligations, with the managing underwriter of such offering and take such other
actions as are reasonably required in order to expedite or facilitate the
disposition of the Registrable Securities, unless such Selling Shareholder has
notified the Company in writing of such Selling Shareholder's election to
exclude all of such Selling Shareholder's Registrable Securities from such
Registration Statement.

         Section 4.4.      Each Selling Shareholder agrees that, upon receipt of
any notice from the Company of the happening of any event of the kind described
in Section 3.6 or 3.7, such Selling Shareholder will immediately discontinue
disposition of Registrable Securities pursuant to the Registration Statement
covering such Registrable Securities until such Selling Shareholder's receipt of
the copies of the supplemented or amended prospectus contemplated by Section 3.6
or 3.7 and, if so directed by the Company, such Selling Shareholder shall
deliver to the Company or destroy all copies in such Selling Shareholder's
possession, of the prospectus covering such Registrable Securities current at
the time of receipt of such notice.

         Section 4.5.      No Selling Shareholder may participate in any
underwritten registration hereunder unless such Selling Shareholder (i) agrees
to sell such Selling Shareholder's Registrable Securities on the basis provided
in any underwriting arrangements in usual and

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customary form entered into by the Company, (ii) completes and executes all
questionnaires, powers of attorney, indemnities, underwriting agreements and
other documents reasonably required under the terms of such underwriting
arrangements, and (iii) agrees to pay its pro rata share of all underwriting
discounts and commissions and any expenses in excess of those payable by the
Company pursuant to Section 5 below.

         Section 4.6.      The Selling Shareholder shall comply with all
applicable laws related to a Registration Statement and offering and sale of
securities and all applicable rules and regulations of governmental authorities
in connection therewith (including without limitation the 1933 Act and the 1934
Act (as defined below) and the rules and regulations promulgated by the SEC).

                                    ARTICLE V.
                            EXPENSES OF REGISTRATION

         All reasonable expenses, other than underwriting discounts and
commissions, incurred in connection with registrations, filings or
qualifications pursuant to Sections 2 and 3, including, without limitation, all
registration, listing and qualification fees, printers and accounting fees, the
fees and disbursements of legal counsel for the Company, and the reasonable fees
and disbursements of one legal counsel for all holders of Registrable
Securities, selected by the Selling Shareholder pursuant to Sections 2.2 and 3.8
hereof, shall be borne by the Company.

                                  ARTICLE VI.
                               INDEMNIFICATION

         In the event any Registrable Securities are included in a Registration
Statement under this Agreement:

         Section 6.1.      To the extent permitted by law, the Company will
indemnify, hold harmless and defend (i) each Selling Shareholder who holds such
Registrable Securities, (ii) the directors, officers, partners, employees,
agents and each person who controls any Selling Shareholder within the meaning
of the 1933 Act or the Securities Exchange Act of 1934, as amended (the "1934
ACT"), if any, (iii) any underwriter (as defined in the 1933 Act) for the
Selling Shareholder, and (iv) the directors, officers, partners, employees and
each person who controls any such underwriter within the meaning of the 1933 Act
or the 1934 Act, if any (each, an "INDEMNIFIED PERSON"), against any joint or
several losses, claims, damages, liabilities or expenses (collectively, together
with actions, proceedings or inquiries by any regulatory or self-regulatory
organization, whether commenced or threatened, in respect thereof, "CLAIMS") to
which any of them may become subject insofar as such Claims arise out of or are
based upon: (i) any untrue statement or alleged untrue statement of a material
fact in a Registration Statement or the omission or alleged omission to state
therein a material fact required to be stated or necessary to make the
statements therein not misleading; (ii) any untrue statement or alleged untrue
statement of a material fact contained in any preliminary prospectus if used
prior to the effective date of such Registration Statement, or contained in the
final prospectus (as amended or supplemented, if the Company files any amendment
thereof or supplement thereto with the SEC) or the omission or alleged omission
to state therein any material fact necessary to make the statements made
therein, in light of the circumstances under which the statements therein were

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made, not misleading; or (iii) any violation or alleged violation by the Company
of the 1933 Act, the 1934 Act, any other law, including, without limitation, any
state securities law, or any rule or regulation thereunder relating to the offer
or sale of the Registrable Securities (the matters in the foregoing clauses (i)
through (iii) being, collectively, "VIOLATIONS"). Subject to the restrictions
set forth in Section 6.3 with respect to the number of legal counsel, the
Company shall reimburse the Indemnified Person, promptly as such expenses are
incurred and are due and payable, for any reasonable legal fees or other
reasonable expenses incurred by them in connection with investigating or
defending any such Claim. Notwithstanding anything to the contrary contained
herein, the indemnification agreement contained in this Section 6.1: (i) shall
not apply to a Claim arising out of or based upon a Violation which occurs in
reliance upon and in conformity with information furnished in writing to the
Company by any Indemnified Person or underwriter for such Indemnified Person
expressly for use in connection with the preparation of such Registration
Statement or any such amendment thereof or supplement thereto; (ii) shall not
apply to amounts paid in settlement of any Claim if such settlement is effected
without the prior written consent of the Company, which consent shall not be
unreasonably withheld; (iii) with respect to any preliminary prospectus, shall
not inure to the benefit of any Indemnified Person if the untrue statement or
omission of material fact contained in the preliminary prospectus was corrected
on a timely basis in the prospectus, as then amended or supplemented, such
corrected prospectus was timely made available by the Company pursuant to
Section 3.3 hereof, and the Indemnified Person was promptly advised in writing
not to use the incorrect prospectus prior to the use giving rise to a Violation
and such Indemnified Person, notwithstanding such advice, used it; and (iv)
shall not apply to any offers to sell or sales made by an Indemnified Person
after receipt of the notice referred to in Section 3.6, clause (ii) and during
the period of the Allowed Delay. Such indemnity shall remain in full force and
effect regardless of any investigation made by or on behalf of the Indemnified
Person and shall survive the transfer of the Registrable Securities by the
Selling Shareholder pursuant to Section 9.

         Section 6.2.      In connection with any Registration Statement in
which an Selling Shareholder is participating, each such Selling Shareholder
agrees severally and not jointly to indemnify, hold harmless and defend, to the
same extent and in the same manner set forth in Section 6.1, the Company, each
of its directors, each of its officers who signs the Registration Statement,
each person, if any, who controls the Company within the meaning of the 1933 Act
or the 1934 Act, any underwriter and any other shareholder selling securities
pursuant to the Registration Statement or any of its directors or officers or
any person who controls such shareholder or underwriter within the meaning of
the 1933 Act or the 1934 Act (collectively and together with an Indemnified
Person, an "INDEMNIFIED PARTY"), against any Claim to which any of them may
become subject, under the 1933 Act, the 1934 Act or otherwise, insofar as such
Claim arises out of or is based upon (i) any Violation, in each case to the
extent (and only to the extent) that such Violation occurs in reliance upon and
in conformity with written information furnished to the Company by such Selling
Shareholder expressly for use in connection with such Registration Statement or
(ii) any offers to sell or sales by such Selling Shareholder after receipt by
such Selling Shareholder of the notice referred to in Section 3.6, clause (ii)
and during the period of the Allowed Delay; and subject to Section 6.3, such
Selling Shareholder will reimburse any legal or other expenses (promptly as such
expenses are incurred and are due and payable) reasonably incurred by them in
connection with investigating or defending any such Claim; provided, however,
that the indemnity agreement contained in this Section 6.2 shall not apply to
amounts paid in settlement of any Claim if such settlement is effected without
the prior written

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consent of such Selling Shareholder, which consent shall not be unreasonably
withheld; provided, further, however, that the Selling Shareholder shall be
liable under this Agreement (including this Section 6.2 and Section 7) for only
that amount as does not exceed the net proceeds to such Selling Shareholder as a
result of the sale of Registrable Securities pursuant to such Registration
Statement. Such indemnity shall remain in full force and effect regardless of
any investigation made by or on behalf of such Indemnified Party and shall
survive the transfer of the Registrable Securities by the Selling Shareholder
pursuant to Section 9. Notwithstanding anything to the contrary contained
herein, the indemnification agreement contained in this Section 6.2 with respect
to any preliminary prospectus shall not inure to the benefit of any Indemnified
Party if the untrue statement or omission of material fact contained in the
preliminary prospectus was corrected on a timely basis in the prospectus, as
then amended or supplemented, and the Indemnified Party was promptly advised in
writing not to use the incorrect information prior to the use giving rise to a
Violation and such Indemnified Party, notwithstanding such advice, used it.

         Section 6.3.      Promptly after receipt by an Indemnified Party under
this Section 6 of notice of the commencement of any action (including any
governmental action), such Indemnified Party shall, if a Claim in respect
thereof is to be made against any indemnifying party under this Section 6,
deliver to the indemnifying party a written notice of the commencement thereof,
and the indemnifying party shall have the right to participate in, and, to the
extent the indemnifying party so desires, jointly with any other indemnifying
party similarly noticed, to assume control of the defense thereof with counsel
selected by the indemnifying party and reasonably satisfactory to the
Indemnified Party, as the case may be; provided, however, that an Indemnified
Party shall have the right to retain its own counsel with the fees and expenses
to be paid by the indemnifying party, if, in the reasonable opinion of counsel
retained by the indemnifying party, the representation by such counsel of the
Indemnified Party and the indemnifying party would be inappropriate due to
actual or potential differing interests between such Indemnified Party and any
other party represented by such counsel in such proceeding. The indemnifying
party shall pay for only one separate legal counsel for the Indemnified Persons
or the Indemnified Parties, as applicable, and such legal counsel shall be
selected by the Selling Shareholder, if the Selling Shareholder is entitled to
indemnification hereunder, or the Company, if the Company is entitled to
indemnification hereunder, as applicable. The failure to deliver written notice
to the indemnifying party within a reasonable time of the commencement of any
such action shall not relieve such indemnifying party of any liability to the
Indemnified Party under this Section 6, except to the extent that the
indemnifying party is actually prejudiced in its ability to defend such action.
The indemnification required by this Section 6 shall be made by periodic
payments of the amount thereof during the course of the investigation or
defense, as such expense, loss, damage or liability is incurred and is due and
payable.

                                  ARTICLE VII.
                                  CONTRIBUTION

         To the extent any indemnification by an indemnifying party is
prohibited or limited by law, the indemnifying party agrees to make the maximum
contribution with respect to any amounts for which it would otherwise be liable
under Section 6 to the fullest extent permitted by law; provided, however, that
(i) no contribution shall be made under circumstances where the indemnifying
party would not have been liable for indemnification under the fault standards
set

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forth in Section 6, (ii) no seller of Registrable Securities guilty of
fraudulent misrepresentation (within the meaning of Section 11(f) of the 1933
Act) shall be entitled to contribution from any seller of Registrable Securities
who was not guilty of such fraudulent misrepresentation, and (iii) contribution
(together with any indemnification or other obligations under this Agreement) by
any seller of Registrable Securities shall be limited in amount to the net
amount of proceeds received by such seller from the sale of such Registrable
Securities.

                                 ARTICLE VIII.
                           REPORTS UNDER THE 1934 ACT

         With a view to making available to the Selling Shareholder the benefits
of Rule 144 promulgated under the 1933 Act or any other similar rule or
regulation of the SEC that may at any time permit the Selling Shareholder to
sell securities of the Company to the public without registration ("RULE 144"),
the Company agrees to:

                  (a)      make and keep public information available, as those
         terms are understood and defined in Rule 144;

                  (b)      file with the SEC in a timely manner all reports and
         other documents required of the Company under the 1933 Act and the 1934
         Act so long as the Company remains subject to such requirements and the
         filing of such reports and other documents is required for the
         applicable provisions of Rule 144; and

                  (c)      furnish to each Selling Shareholder so long as such
         Selling Shareholder owns Registrable Securities, promptly upon request,
         such information as may be reasonably requested to permit such Selling
         Shareholder to sell such securities pursuant to Rule 144 without
         registration.

                                  ARTICLE IX.
                        AMENDMENT OF REGISTRATION RIGHTS

         Provisions of this Agreement may be amended and the observance thereof
may be waived (either generally or in a particular instance and either
retroactively or prospectively), only with written consent of the Company and
the Selling Shareholder.

                                   ARTICLE X.
                                    REMEDIES

         In the event the Company fails to file with the SEC a Registration
Statement with respect to all of the Registrable Securities on or before the
Filing Date, and such failure is not due to any breach of its obligations by the
Selling Shareholder hereunder or any delay caused by the Selling Shareholder,
the Selling Shareholder shall have the following alternative (and not
cumulative) remedies: (i) if such Registration Statement is not filed within
thirty (30) days following the Filing Date, the Selling Shareholder shall have
an option (the "Put Option") pursuant to which the Selling Shareholder may by
written demand upon the Company require the Company to purchase from the Selling
Shareholder all of the Registrable Securities for a purchase price equal to a
total of One Million Four Hundred Fifty Thousand Dollars ($1,450,000), plus
interest at the

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rate of ten percent (10%) per annum on the unpaid balance of the purchase price,
which interest shall begin to accrue on the unpaid balance of the purchase price
fifteen (15) days after the Company receives written demand for such purchase
from the Selling Shareholder, and the Closing on the purchase and sale of the
Registrable Securities pursuant to the exercise of such Put Option shall occur
not later than fifteen (15) days following the date of exercise of such option;
(ii) obtain from the Company in immediately available funds an amount equal to
the total damages suffered by Selling Shareholder as a result of the failure to
timely file such Registration Statement, including litigation costs and
reasonable attorneys fees incurred by Selling Shareholder in obtaining such
remedy; or (iii) specific performance of this Agreement against the Company and
require the Company to fully perform all of its obligations under this
Agreement.

                                   ARTICLE XI.
                                  MISCELLANEOUS

         Section 11.1.     A person or entity is deemed to be a holder of
Registrable Securities whenever such person or entity owns of record such
Registrable Securities. If the Company receives conflicting instructions,
notices or elections from two or more persons or entities with respect to the
same Registrable Securities, the Company shall act upon the basis of
instructions, notice or election received from the registered owner of such
Registrable Securities.

         Section 11.2.     Any notices required or permitted to be given under
the terms hereof shall be given in the manner sent by certified or registered
mail (return receipt requested) or delivered personally or by courier (including
a recognized overnight delivery service) or by facsimile and shall be effective
five (5) calendar days after being placed in the mail, if mailed by regular
United States mail, or upon receipt, if delivered personally or by courier
(including a recognized overnight delivery service) or by facsimile, in each
case addressed to a party. The addresses and facsimile numbers for such
communications shall be:

                           If to the Company:

                           Zix Corporation
                           2711 North Haskell Avenue
                           Suite 2300 LB36
                           Dallas, Texas 75246
                           Attention: General Counsel
                           Facsimile: (214) 515-7538

If to Selling Shareholder, to the address and facsimile number set forth in the
Asset Purchase Agreement with a copy to the counsel specified in the Asset
Purchase Agreement or (in the case of permitted assigns, below the Selling
Shareholder's signature on the signature page to this Agreement).

         Section 11.3.     Failure of any party to exercise any right or remedy
under this Agreement or otherwise, or delay by a party in exercising such right
or remedy, shall not operate as a waiver thereof.

                                       11

<PAGE>

         Section 11.4.     GOVERNING LAW. THIS AGREEMENT WILL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS WITHOUT REFERENCE TO
THE PRINCIPLES OF CONFLICT OF LAWS OR ANY OTHER PRINCIPLE THAT COULD RESULT IN
THE APPLICATION OF THE LAWS OF ANY OTHER JURISDICTION.

         Section 11.5.     This Agreement and the Asset Purchase Agreement
(including all schedules and exhibits thereto) constitute the entire agreement
among the parties hereto with respect to the subject matter hereof and thereof.
There are no restrictions, promises, warranties or undertakings, other than
those set forth or referred to herein and therein. This Agreement and the Asset
Purchase Agreement supersede all prior agreements and understandings among the
parties hereto with respect to the subject matter hereof and thereof.

         Section 11.6.     The Selling Shareholder may assign its rights
hereunder to the current shareholders of the Selling Shareholder that execute a
joinder page indicating their agreement to be bound to the terms and conditions
of this Agreement. This Agreement shall inure to the benefit of and be binding
upon the successors and assigns of each of the parties hereto.

         Section 11.7.     The headings in this Agreement are for convenience of
reference only and shall not limit or otherwise affect the meaning hereof.

         Section 11.8.     This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original but all of which shall
constitute one and the same agreement. This Agreement, once executed by a party,
may be delivered to the other party hereto by facsimile transmission of a copy
of this Agreement bearing the signature of the party so delivering this
Agreement.

         Section 11.9.     Each party shall do and perform, or cause to be done
and performed, all such further acts and things, and shall execute and deliver
all such other agreements, certificates, instruments and documents, as the other
party may reasonably request in order to carry out the intent and accomplish the
purposes of this Agreement and the consummation of the transactions contemplated
hereby.

         Section 11.10.    The language used in this Agreement will be deemed to
be the language chosen by the parties to express their mutual intent, and no
rules of strict construction will be applied against any party.

         Section 11.11.    In the event that any provision of this Agreement is
invalid or unenforceable under any applicable statute or rule of law, then such
provision shall be deemed inoperative to the extent that it may conflict
therewith and shall be deemed modified to conform with such statute or rule of
law. Any provision hereof which may prove invalid or unenforceable under any law
shall not affect the validity or enforceability of any other provision hereof.

                [REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK]

                                       12

<PAGE>

         IN WITNESS WHEREOF, the Company and the Selling Shareholder have caused
this Agreement to be duly executed as of the date first above written.

                                            ZIX CORPORATION

                                            By:
                                                 Name:
                                                 Title:

                                            POCKETSCIPT L.L.C.

                                            By:
                                                 Name:
                                                 Title:

                                       13

<PAGE>

                                     JOINDER

         The undersigned, who represents that it is a member of PocketScript
L.L.C., hereby executes this signature page to that certain Registration Rights
Agreement (the "Registration Rights Agreement"), dated July 22, 2003, between
PocketScript L.L.C. and Zix Corporation, thereby indicating the undersigned's
agreement to the terms and conditions of the Registration Rights Agreement, as
fully and effectively as if the undersigned had executed and delivered this page
at the time originally executed by each of Pocket Script L.L.C. and Zix
Corporation.

                                           _______________________________
                                           Name: _________________________
                                           Date: _________________________

                                           Address: _____________________
                                           _____________________
                                           _____________________

                                       14<PAGE>
                                                                     EXHIBIT 4.1

             Warrant to Purchase up to 73,821 Shares of Common Stock

                                       of

                          Northfield Laboratories Inc.

                            PLACEMENT AGENT'S WARRANT

                              Dated: July 28, 2003

         This certifies that SG COWEN SECURITIES CORPORATION (herein sometimes
called the "PLACEMENT AGENT") or its permitted transferee (the Placement Agent
or any such transferee is sometimes herein called the "HOLDER") is entitled to
purchase from NORTHFIELD LABORATORIES INC., a Delaware corporation (the
"COMPANY"), at the price and during the period as hereinafter specified, up to
73,821 shares (the "SHARES") (equal to three percent (3%) of the number of
Shares (as defined below)) of common stock, $0.01 par value per share of the
Company (the "COMMON STOCK") sold pursuant to the purchase agreements in the
form included as Exhibit A to the Placement Agency Agreement (defined below) at
a purchase price of $[_____] per share (equal to the average volume weighted
closing price of a Share, as reported on the Nasdaq National Market for the five
Trading Days (as defined herein) preceding the Closing Date (as defined in the
Placement Agency Agreement), subject to adjustment as described below (as so
adjusted from time to time, the "EXERCISE PRICE")), at any time during the
four-(4) year period commencing one (1) year from the Closing Date.

         This Placement Agent's Warrant (the "PLACEMENT AGENT'S WARRANT") is
issued pursuant to a Placement Agency Agreement between the Company and SG Cowen
Securities Corporation, as Placement Agent, in connection with a public
offering, through the commercially reasonable efforts of the Placement Agent, of
up to 2,460,714 Shares as therein described (the "PLACEMENT AGENCY AGREEMENT").
All capitalized terms used herein and not otherwise defined, shall have the
meanings ascribed to such terms in the Placement Agency Agreement.

         1. EXERCISE. The rights represented by the Placement Agent's Warrant
shall be exercisable at the Exercise Price, and during the periods as follows:

                  (a) During the period from the Closing Date to and through
July 27, 2004 (the "FIRST ANNIVERSARY DATE"), inclusive, the Holder shall have
no right to purchase any Shares hereunder.

                  (b) At any time and from time to time between, July 28, 2004
and July 29, 2008, (the expiration of five (5) years from the Closing Date, i.e.
the "EXPIRATION DATE") inclusive, the Holder shall have the right to purchase
such number of Shares hereunder as is determined pursuant to Section 1(c) hereof
at the Exercise Price.

<PAGE>

                  (c) This Placement Agent's Warrant shall be exercisable for
such number of shares (rounded to the nearest whole number) as is equal to the
aggregate number of shares of Firm Stock plus the aggregate number of shares of
Optional Stock purchased by the Purchasers at the First Closing and any Option
Closings multiplied by 0.03.

                  (d) After the Expiration Date, the Holder shall have no right
to purchase all or any portion of the Shares hereunder.

         2. PAYMENT FOR SHARES; ISSUANCE OF CERTIFICATES; NET EXERCISE.

                  (a) The rights represented by the Placement Agent's Warrant
may be exercised at any time within the periods above specified, in whole or in
part, by (i) the surrender of the Placement Agent's Warrant (with the purchase
form at the end hereof properly executed) at the principal executive office of
the Company (or such other office or agency of the Company as it may designate
by notice in writing to the Holder at the address of the Holder appearing on the
books of the Company); (ii) payment to the Company of the Exercise Price then in
effect for the number of Shares specified in the above-mentioned purchase form
together with applicable stock transfer taxes, if any; and (iii) delivery to the
Company of a duly executed agreement signed by the person(s) designated in the
purchase form to the effect that such person(s) agree(s) to be bound by the
provisions of Section 6 and subsections (b), (c) and (d) of Section 7 hereof.
The Placement Agent's Warrant shall be deemed to have been exercised, in whole
or in part to the extent specified, immediately prior to the close of business
on the date the Placement Agent's Warrant is surrendered and payment is made in
accordance with the foregoing provisions of this Section 2, and the person or
persons in whose name or names the certificates for the Shares shall be issuable
upon such exercise shall become the holder or holders of record of such Shares
at that time and date. The Shares and the certificates for the Shares so
purchased shall be delivered to the Holder within a reasonable time, not
exceeding ten (10) business days, after the rights represented by this Placement
Agent's Warrant shall have been so exercised.

                  (b) Notwithstanding anything to the contrary contained in
Section 2(a), the Holder may elect to exercise this Placement Agent's Warrant in
whole or in part on a "cashless exercise basis" by receiving Shares equal to the
value (as determined below) of this Placement Agent's Warrant, or any part
hereof, upon surrender of the Placement Agent's Warrant at the principal office
of the Company together with notice of such election in which event the Company
shall issue to the Holder a number of Shares computed using the following
formula:

                                   X = Y(A-B)
                                       ------
                                         A

         Where:            X =  the number of Shares to be issued to the Holder;

                           Y =  the number of Shares issuable upon exercise of
                                this Placement Agent's Warrant or, if only a
                                portion of this Placement Agent's Warrant is
                                being exercised, the portion of this Placement
                                Agent's Warrant being canceled (at the date of
                                such calculation);

                                       2
<PAGE>

                           A =  the fair market value of one share of Common
                                Stock (at the date of such calculation);

                           B =  the Exercise Price (as adjusted to the date of
                                such calculation).

For the purpose of any computation under this Subsection 2(b), the fair market
value per share of Common Stock at any date shall be deemed to be the closing
price of the Common Stock on the Trading Day immediately preceding the date as
of which the fair market value is being determined, provided that if the Common
Stock is not then listed on any market or exchange, then the fair market value
shall be the average of the closing bid prices for the Common Stock on the OTC
Bulletin Board, or, if such is not available, the Pink Sheets LLC (formerly the
National Quotation Bureau), or otherwise the average of the closing bid prices
for the Common Stock quoted by two market-makers of the Common Stock, or
otherwise such fair market value shall be determined in good faith by the
Corporation and the Holders. "TRADING Day" shall mean any day on which the
principal United States securities exchange or trading market on which the
Common Stock is listed or traded (the "PRINCIPAL MARKET") as reported by
Bloomberg Financial Markets ("BLOOMBERG'S") is open for trading. "Closing price"
shall mean the last sale price for the Common Stock on the Principal Market on
any particular Trading Day.

         3. TRANSFER. (a) The Placement Agent's Warrant shall not be sold,
transferred, assigned, or hypothecated for a period of one (1) year commencing
on the Closing Date, except that it may be transferred to successors of the
Holder.

                  (b) Any transfer of this Placement Agent's Warrant shall be
effected by the Holder by (i) executing the form of assignment at the end hereof
and (ii) surrendering the Placement Agent's Warrant for cancellation at the
office or agency of the Company referred to in Section 2 hereof, accompanied by
(x) a written instrument of transfer in form reasonably satisfactory by the
Company, duly executed by the registered Holder thereof or by the duly appointed
legal representative thereof or by a duly authorized attorney-in-fact, (y) a
certificate (signed by an officer of the Holder if the Holder is a corporation)
stating that each transferee is a permitted transferee under this Section 3; and
(z) an opinion of counsel, reasonably satisfactory in form and substance to the
Company, to the effect that this Placement Agent's Warrant or the Shares, as
applicable, may be sold or otherwise transferred without registration under the
Securities Act of 1933, as amended (the "ACT").

                  Upon any transfer of this Placement Agent's Warrant or any
part thereof in accordance with the first sentence of this Section 3(b), the
Company shall issue, in the name or names specified by the Holder (including the
Holder), a new Placement Agent's Warrant or Warrants of like tenor and
representing in the aggregate rights to purchase the same number of Shares as
are purchasable hereunder at such time.

                  (c) Any attempted transfer of this Placement Agent's Warrant
or any part thereof in violation of this Section 3 shall be null and void ab
initio.

         4. SHARES TO BE FULLY PAID; RESERVATION OF SHARES. The Company
covenants and agrees that all Shares which may be purchased hereunder will, upon
issuance and delivery against payment therefor of the requisite purchase price,
be duly

                                       3
<PAGE>

and validly issued, fully paid and nonassessable. The Company further covenants
and agrees that, during the periods within which the Placement Agent's Warrant
may be exercised, the Company will at all times have authorized and reserved a
sufficient number of shares of its Common Stock to provide for the exercise of
the Placement Agent's Warrant.

         5. NO VOTING OR DIVIDEND RIGHTS. The Placement Agent's Warrant shall
not entitle the Holder to any voting rights or other rights, including without
limitation notice of meetings of other actions or receipt of dividends, as a
stockholder of the Company.

         6. REGISTRATION RIGHTS. The Company covenants and agrees that, during
the periods within which the Placement Agent's Warrant may be exercised, the
Company will, upon the written request of the Placement Agent, use its
commercially reasonable efforts to amend or supplement the registration
statement filed on Form S-3 in connection with the offering of the Common Stock
that is subject to the Placement Agency Agreement in order to include any
additional information as, in the opinion of counsel to the Placement Agent, may
be required to permit a public offering of all or any of the Shares underlying
the Placement Agent's Warrant (the "REGISTRABLE SECURITIES"). In the event that,
during any such periods, the Registrable Securities may not be publicly offered
under such registration statement, the Holders of Placement Agent's Warrants
shall have the following registration rights:

                   (a) Except as provided in Section 6(b), the Company shall
advise the Holder or its permitted transferee, whether the Holder holds the
Placement Agent's Warrant or has exercised the Placement Agent's Warrant and
holds Shares, by written notice at least ten (10) business days prior to the
filing of any new registration statement thereto under the Act, covering any
equity securities of the Company, for its own account or for the account of
others, except for any registration statement filed on Form S-4 or S-8 (or other
comparable form), and will, during the four (4) year period from the First
Anniversary Date, upon the request of the Holder, include in any such new
registration statement (the "REGISTRATION STATEMENT") such information as may be
required to permit a public offering of, all or any of the Registrable
Securities.

                  (b) At any time during the four (4) year period beginning on
the First Anniversary Date, a 50% Holder (as defined below) may request that the
Company register under the Act any and all of the Registrable Securities held by
such 50% Holder, at the Company's expense (except as provided below). Except as
otherwise expressly provided herein, the holders of Registrable Securities may
exercise the demand registration rights provided in this Section 6(b) only on
one occasion. Upon the receipt of any such notice, the Company will promptly,
but no later than four weeks after receipt of such notice, file a post-effective
amendment to any existing registration statement or a new registration statement
pursuant to the Act (such post-effective amendment or new registration
statement, a "DEMAND REGISTRATION STATEMENT"), so that such designated
Registrable Securities may be publicly sold under the Act as promptly as
practicable thereafter and the Company shall, subject to Section 6(h), use its
commercially reasonable efforts to cause such Demand Registration Statement to
become effective (including the taking of such reasonable steps as are necessary
to obtain the removal of any stop order) within 120 days after the receipt of
such notice, provided, that such 50%

                                       4
<PAGE>

Holder shall furnish the Company with appropriate information in connection
therewith as the Company may reasonably request in writing. The 50% Holder may,
at its option, request the registration of any of Registrable Securities in a
registration statement made by the Company as contemplated by Section 6(a) or in
connection with a request made pursuant to this Section 6(b), in either case
prior to acquisition of the Shares issuable upon exercise of the Placement
Agent's Warrant. Subject to Section 6(h), within ten days after receiving any
such notice pursuant to this Section 6(b), the Company shall give notice to any
other Holders of the Placement Agent's Warrant, advising that the Company is
proceeding with such Demand Registration Statement and offering to include
therein, pursuant to Section 6(a), the Shares underlying that part of the
Placement Agent's Warrant held by the other Holders, provided that they shall
furnish the Company with such appropriate information (relating to the
intentions of such Holders) in connection therewith as the Company shall
reasonably request in writing.

                  (c) The term "50% HOLDER" as used in this Section 6 shall mean
the Holder(s) of at least 50% of the Placement Agent's Warrant and/or the Shares
underlying the Placement Agent's Warrant upon the initial issuance of the
Placement Agent's Warrant, as the same may have been adjusted pursuant to
Section 8.

                  (d) For so long as the Registrable Securities included in any
Registration Statement or Demand Registration Statement remain unsold, but in
any event not longer than 270 days after the date of effectiveness of such
Registration Statement or Demand Registration Statement (plus the number of
days, if any, that such Registration Statement or Demand Registration Statement
has been suspended pursuant to the provisions of Section 6(h)), the Company
shall, subject to Section 6(h), use its commercially reasonable efforts to (i)
maintain the effectiveness of such Registration Statement or Demand Registration
Statement; (ii) timely file all reports required under the Securities Exchange
Act of 1934, as amended, and the rules and regulations of the Securities and
Exchange Commission (the "COMMISSION") thereunder; (iii) file such
post-effective amendments to the Registration Statement or Demand Registration
Statement as may be necessary so that the Registration Statement or Demand
Registration Statement does not contain any misstatement of a material fact or
omit to state any material fact required to make the statements therein not
misleading; (iv) supply prospectuses and such other documents as any Holder
whose Registrable Securities are included in such Registration Statement or
Demand Registration Statement may reasonably request in order to facilitate the
public sale or other disposition of such Registrable Securities; (v) register
and qualify any of the Registrable Securities for sale in such jurisdictions
within the United States (x) as any such Holder designates and (y) with respect
to which the Company obtained a qualification in connection with its initial
public offering, provided that the nothing in this clause (v) shall require the
Company to qualify to do business as a foreign corporation, submit to taxation
in any jurisdiction or to file a general consent to service of process in any
jurisdiction in which it is not otherwise so qualified or required to file such
a consent at the time; and (vi) do any and all other acts and things which may
be necessary or desirable to enable any such Holder to consummate the public
sale or other disposition of the Registrable Securities included in the
Registration Statement or Demand Registration Statement, all at no expense to
such Holder or the Placement Agent (except as provided in the immediately
following sentence). All costs and expenses in connection with any Registration
Statement or

                                       5
<PAGE>

Demand Registration Statement shall be borne by the Company, except that the
Holder(s) shall bear the fees of their own counsel and any other advisors
retained by them and any underwriting discounts or sales or other commissions
applicable to any of the Registrable Securities sold by them. In connection with
any Registration Statement or Demand Registration Statement, the Company shall
furnish indemnification in the manner provided in Section 7 hereof, and each
Holder whose Registrable Securities are included therein shall furnish
information and indemnification in the manner provided in Section 7. Subject to
Section 6(g), the Company shall have the right to include additional shares of
Common Stock to be issued and sold by the Company in any Demand Registration
Statement.

                  (e) Notwithstanding the foregoing set forth in this Section 6,
the Company shall not be required to include in any Registration Statement or
any Demand Registration Statement any Registrable Securities which in the
opinion of counsel to the Company (which opinion is reasonably acceptable to
counsel to the Placement Agent) would be saleable without restriction or
limitation under the holding period requirements or volume limitations under
Rule 144 (or its successor) if the Placement Agent's Warrant was exercised
pursuant to Section 2(b) herein.

                  (f) If any registration pursuant to this Section 6 is in the
form of an underwritten offering, the Company will select and obtain the
investment banker or investment bankers and manager or managers that will
administer the offering. The Company shall (together with each Holder whose
Registrable Securities are included in such offering) enter into an underwriting
agreement in customary form with the managing underwriter selected for such
underwriting. If any Holder disapproves of the terms of the underwriting, it may
elect to withdraw therefrom by written notice to the Company and the managing
underwriter, and upon such withdrawal the original request of such Holder to
cause Registrable Securities to be registered shall not be deemed to constitute
a request for registration pursuant to Section 6(b), provided that the
withdrawal of one or more Holders shall not affect the determination of whether
any request made pursuant to Section 6(b) was made by a 50% Holder, and provided
further that if all Holders who have requested inclusion of their shares in a
Demand Registration pursuant to Section 6(b) withdraw their Registrable
Securities, then, notwithstanding anything to the contrary in this Placement
Agent's Warrant, any Holders who request registration of Registrable Securities
pursuant to Section 6(b) in the future shall be responsible for and pay all
expenses incurred by the Company in connection with such future registration.

                  (g) (i) In the event that any registration pursuant to Section
6(a) shall be in connection with an underwritten offering, and the managing
underwriter determines in good faith and advises in writing that the number of
Registrable Securities to be included in such offering, together with the number
of shares of Common Stock to be included in the Registration Statement by the
Company or other holders of the Company's securities with the right to request
inclusion in the Registration Statement, if any, exceeds the number of shares of
Common Stock that it is advisable to offer and sell at such time or would
interfere with the successful marketing of the Common Stock covered by the
Registration Statement, then priority for including shares of Common Stock in
the Registration Statement, up to the number advised by the managing
underwriter, shall be allocated first, to the Company and each other person who
has

                                       6
<PAGE>

requested inclusion of shares of Common Stock pursuant to a "demand"
registration right, pro rata in proportion to the respective number of shares of
Common Stock to be included by them, and second, to the extent of any remaining
capacity as advised by the managing underwriter, to the Holders requesting
registration of their Registrable Securities and each other person who has
requested inclusion of shares of Common Stock pursuant to a "piggyback"
registration right, pro rata in proportion to the respective number of shares of
Common Stock (including Registrable Securities) to be included by them. (ii) In
the event that any registration pursuant to Section 6(b) shall be in connection
with an underwritten offering, and the managing underwriter determines in good
faith and advises in writing that the number of Registrable Securities to be
included in such offering, together with the number of shares of Common Stock to
be included in the Demand Registration Statement by the Company or other holders
of the Company's securities with the right to request inclusion in the Demand
Registration Statement, if any, exceeds the number of shares of Common Stock
that it is advisable to offer and sell at such time or would interfere with the
successful marketing of the Common Stock covered by the Demand Registration
Statement, then priority for including shares of Common Stock in the Demand
Registration Statement, up to the number advised by the managing underwriter,
shall be allocated first, to the 50% Holder and each other person who has
requested inclusion of shares of Common Stock pursuant to a "demand"
registration right, pro rata in proportion to the respective number of shares of
Common Stock to be included by them, and second, to the extent of any remaining
capacity as advised by the managing underwriter, to the Company and each other
person (including any Holder who is not a 50% Holder and who requests inclusion
of Registrable Securities in the Demand Registration Statement pursuant to
Section 6(a)) who has requested inclusion of shares of Common Stock pursuant to
a "piggyback" registration right, pro rata in proportion to the respective
number of shares of Common Stock (including Registrable Securities) to be
included by them.

                  (h) In any registration initiated by the Company or by any
person having "demand" registration rights (other than a 50% Holder exercising
such rights pursuant to Section 6(b)) in which Holders request inclusion of
their Registrable Securities pursuant to Section 6(a), if at any time after
giving notice of its intention to register securities and prior to the effective
date of the Registration Statement the Company or such other person shall
determine for any reason not to register or to delay registration of it
securities, the Company may, at its election, give written notice of such
determination to each Holder that has requested inclusion of Registrable
Securities in the Registration Statement and (x) in the case of a determination
not to register, shall be relieved of its obligation to register any Registrable
Securities in connection with such registration and (y) in the case of a
determination to delay registering, shall be permitted to delay registering any
Registrable Securities for the same period as the delay in registering such
other securities. If (i) at any time when a prospectus relating to Registrable
Securities is required to be delivered under the Act, the Company discovers
that, or any event occurs as a result of which, the prospectus (including any
supplement thereto) included in any Registration Statement or Demand
Registration Statement, as then in effect, includes an untrue statement of a
material fact or omits to state any material fact required to be stated therein
or necessary to make the statements therein, in the light of the circumstances
under which they were made, not misleading, or (ii) the

                                       7
<PAGE>

Commission issues any stop order suspending the effectiveness of any
Registration Statement or proceedings are initiated or threatened for that
purpose, then the Company shall promptly deliver a written notice to such effect
to each Holder whose Registrable Securities are included in such Registration
Statement or Demand Registration Statement, and each such Holder shall
immediately upon receipt of such notice discontinue its disposition of
Registrable Securities pursuant to such Registration Statement or Demand
Registration Statement until its receipt of the copies of the supplemented or
amended prospectus contemplated by the immediately following sentence and, if so
directed by the Company, shall deliver to the Company (at the Company's expense)
all copies, other than permanent file copies, then in such Holder's possession
of the prospectus or prospectus supplement relating to such Registrable
Securities current at the time of receipt of such notice. As promptly as
practicable following the event or discovery referred to in clause (i) of the
immediately preceding sentence, the Company shall prepare and furnish to the
Holders whose Registrable Securities are included in such Registration Statement
or Demand Registration Statement a reasonable number of copies of an amendment
or supplement of such prospectus so that, as thereafter delivered to purchasers
of such Registrable Securities, such prospectus shall not include an untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary to make the statements therein, in the light of the
circumstances under which they were made, not misleading. Notwithstanding
anything to the contrary in this Section 6 if the filing or maintenance of any
Registration Statement or Demand Registration Statement would require the
Company to make a disclosure that would, in the reasonable judgment of the
Company's Board of Directors, have a material adverse effect on the business,
operations, properties, prospects or financial condition of the Company or on
pending or imminent transactions, the Company shall have the right, exercisable
for a period not to exceed in the aggregate 60 consecutive calendar days in any
period of twelve consecutive months (the "Blackout Period") upon written notice
to the Holders, to delay the filing of any Registration Statement or Demand
Registration Statement or of any amendment thereto, to suspend its obligation to
maintain the effectiveness of any Registration Statement or Demand Registration
Statement and to suspend the use of any prospectus or prospectus supplement in
connection with any Registration Statement or Demand Registration Statement.
Each Holder agrees that upon receipt of any such notice from the Company, it
shall immediately cease all efforts to dispose of Registrable Securities
pursuant to such Registration Statement or Demand Registration Statement until
such time as the Company shall notify it of the end of such restrictions or, if
earlier, the expiration of the Blackout Period.

         7. INDEMNIFICATION. (a) Whenever pursuant to Section 6 a Registration
Statement or Demand Registration Statement relating to any Shares issued upon
exercise of the Placement Agent's Warrant is filed under the Act, amended or
supplemented, the Company will indemnify and hold harmless each Holder of the
securities covered by such Registration Statement or Demand Registration
Statement, amendment or supplement (such Holder being hereinafter called the
"DISTRIBUTING HOLDER"), and each person, if any, who controls (within the
meaning of the Act) the Distributing Holder, and each underwriter (within the
meaning of the Act) of such securities and each person, if any, who controls
(within the meaning of the Act) any such underwriter, against any losses,
claims, damages or liabilities, joint or several, to which the Distributing
Holder,

                                       8
<PAGE>

any such controlling person or any such underwriter may become subject, under
the Act or otherwise, insofar as such losses, claims, damages or liabilities, or
actions in respect thereof, arise out of or are based upon (i) any untrue
statement or alleged untrue statement of any material fact contained in any such
Registration Statement or Demand Registration Statement as declared effective or
any final prospectus constituting a part thereof or any amendment or supplement
thereto, (ii) the omission or the alleged omission to state therein a material
fact required to be stated therein or necessary to make the statements therein
not misleading or (iii) any act or failure to act, or any alleged act or failure
to act, by any Distributing Holder in connection with, or relating in any manner
to, the Registration Statement or Demand Registration Statement or the offering
contemplated thereby, and which is included as part of or referred to in any
loss, claim, damage, liability or action arising out of or based upon matters
covered by clause (i) or (ii) above; (provided that the Company shall not be
liable in the case of any matter covered by this clause (iii) to the extent that
it is determined in a final judgment by a court of competent jurisdiction that
such loss, claim, damage, liability or action resulted directly from any such
act or failure to act undertaken or omitted to be taken by such Distributing
Holder through its gross negligence or willful misconduct) and will reimburse
the Distributing Holder or such controlling person or underwriter promptly upon
demand for any legal or other expense reasonably incurred by them in connection
with investigating or defending any such loss, claim, damage, liability or
action as such expenses are incurred; provided, however, that the Company will
not be liable in any such case to the extent that any such loss, claim, damage,
liability or action arises out of or is based upon an untrue statement or
alleged untrue statement or omission or alleged omission made in said
Registration Statement or Demand Registration Statement, said preliminary
prospectus, said final prospectus or said amendment or supplement in reliance
upon and in conformity with written information furnished by such Distributing
Holder or any other Distributing Holder for use in the preparation thereof and
provided further, that the indemnity agreement provided in this Section 7(a)
with respect to any preliminary prospectus shall not inure to the benefit of any
Distributing Holder, controlling person of such Distributing Holder, underwriter
or controlling person of such underwriter from whom the person asserting any
losses, claims, charges, liabilities or litigation based upon any untrue
statement or alleged untrue statement of a material fact or omission or alleged
omission to state therein a material fact, received such preliminary prospectus,
if a copy of the prospectus in which such untrue statement or alleged untrue
statement or omission or alleged omission was corrected has not been sent or
given to such person within the time required by the Act and the rules and
regulations of the Commission thereunder. This indemnity agreement is not
exclusive and will be in addition to any liability, which the Company might
otherwise have and shall not limit any rights or remedies that may otherwise be
available at law or in equity to each Distributing Holder.

                  (b) The Distributing Holder will indemnify and hold harmless
the Company, each of its directors, each of its officers who have signed said
Registration Statement or Demand Registration Statement and such amendments and
supplements thereto, and each person, if any, who controls the Company (within
the meaning of the Act) against any losses, claims, damages or liabilities,
joint or several, to which the Company or any such director, officer or
controlling person may become subject, under

                                       9
<PAGE>

the Act or otherwise, insofar as such losses, claims, damages or liabilities, or
actions in respect thereof, arise out of or are based upon (i) any untrue or
alleged untrue statement of any material fact contained in said Registration
Statement or Demand Registration Statement, said preliminary prospectus, said
final prospectus, or said amendment or supplement, or (ii) are based upon the
omission or the alleged omission to state therein a material fact required to be
stated therein or necessary to make the statements therein not misleading, in
each case to the extent, but only to the extent, that such loss, claim, damage
or liability arises out of or is based upon an untrue statement or alleged
untrue statement or omission or alleged omission made in said Registration
Statement or Demand Registration Statement, said preliminary prospectus, said
final prospectus or said amendment or supplement in reliance upon and in
conformity with written information furnished by such Distributing Holder for
use in the preparation thereof; and will reimburse the Company or any such
director, officer or controlling person for any legal or other expenses
reasonably incurred by them in connection with investigating or defending any
such loss, claim, damage, liability or action as such expenses are incurred.
This indemnity agreement is not exclusive and will be in addition to any
liability, which each Distributing Holder might otherwise have and shall not
limit any rights or remedies that may otherwise be available at law or in equity
to the Company.

                  (c) Promptly after receipt by an indemnified party under this
Section 7 of notice of the commencement of any action, such indemnified party
will, if a claim in respect thereof is to be made against an indemnifying party
under this Section 7, notify the indemnifying party in writing of the
commencement thereof, but the omission so to notify the indemnifying party will
not relieve it from any liability which it may have to any indemnified party for
indemnity or contribution to the extent it is not prejudiced as a proximate
result of such failure. In case any such action is brought against any
indemnified party, and such indemnified party seeks or intends to seek indemnity
from an indemnifying party, the indemnifying party will be entitled to
participate in, and, to the extent that it shall elect, jointly with any other
indemnifying party similarly notified, by written notice delivered to the
indemnified party promptly after receiving the aforesaid notice from such
indemnified party, to assume the defense thereof with counsel reasonably
satisfactory to such indemnified party; provided, however, if the defendants in
any such action include both the indemnified party and the indemnifying party
and the indemnified party shall have reasonably concluded that a conflict may
arise between the positions of the indemnifying party and the indemnified party
in conducting the defense of any such action or that there may be legal defenses
available to it and/or other indemnified parties which are different from or
additional to those available to the indemnifying party, the indemnified party
or parties shall have the right to select separate counsel to assume such legal
defenses and to otherwise participate in the defense of such action on behalf of
such indemnified party or parties. Upon receipt of notice from the indemnifying
party to such indemnified party of such indemnifying party's election so to
assume the defense of such action and approval by the indemnified party of
counsel (which approval shall not be unreasonably withheld or delayed), the
indemnifying party will not be liable to such indemnified party under this
Section 7 for any legal or other expenses subsequently incurred by such
indemnified party in connection with the defense thereof unless: (i) the
indemnified party shall have employed separate counsel in accordance with the
proviso to the next preceding sentence (it being understood,

                                       10
<PAGE>

however, that the indemnifying party shall not be liable for the expenses of
more than one separate counsel (together with local counsel), representing the
indemnified parties who are parties to such action); (ii) the indemnifying party
shall not have employed counsel satisfactory to the indemnified party to
represent the indemnified party within a reasonable time after notice of
commencement of the action; or (iii) the indemnifying party has authorized the
employment of counsel for the indemnified party satisfactory to the indemnified
party at the expense of the indemnifying party, in each of which cases the fees
and expenses of counsel shall be at the expense of the indemnifying party.

                  (d) The indemnifying party under this Section 7 shall not be
liable for any settlement of any proceeding effected without its written
consent, which consent shall not be unreasonably withheld or delayed, but if
settled with such consent or if there be a final judgment for the plaintiff, the
indemnifying party agrees to indemnify the indemnified party against any loss,
claim, damage, liability or expense by reason of such settlement or judgment. No
indemnifying party shall, without the prior written consent of the indemnified
party, effect any settlement, compromise or consent to the entry of judgment in
any pending or threatened action, suit or proceeding in respect of which any
indemnified party is or could have been a party and indemnity was or could have
been sought hereunder by such indemnified party, unless such settlement,
compromise or consent includes: (i) an unconditional release of such indemnified
party from all liability on claims that are the subject matter of such action,
suit or proceeding; and (ii) does not include a statement as to or an admission
of fault, culpability or a failure to act by or on behalf of any indemnified
party.

                  (e) Any losses, claims, damages, liabilities or expenses for
which an indemnified party is entitled to indemnification or contribution under
this Section 7 shall be paid by the indemnifying party to the indemnified party
as such losses, claims, damages, liabilities or expenses are incurred, but in
all cases, no later than forty-five (45) days after invoice to the indemnifying
party.

                  (f) If the indemnification provided for in this Section 7 is
unavailable to or insufficient to hold harmless an indemnified party under
Section 7(a) or 7(b) above in respect of any losses, claims, damages or
liabilities (or actions or proceedings in respect thereof) then each
indemnifying party shall contribute to the aggregate amount paid or payable by
such indemnified party in such proportion as is appropriate to reflect the
relative fault of such indemnifying party on the one hand and the Distributing
Holder on the other in connection with the statements or omissions which
resulted in such losses, claims, damages or liabilities (or actions or
proceedings in respect thereof), as well as any other relevant equitable
considerations. The relative fault shall be determined by reference to, among
other things, whether the untrue or alleged untrue statement of a material fact
or the omission or alleged omission to state a material fact relates to
information supplied by the Company or the "control" stockholders on the one
hand or the Distributing Holder on the other and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
statement or omission.

         The Company and each Distributing Holder agree that it would not be
just and equitable if contributions pursuant to this Section 7(f) were
determined by pro rata allocation or by any other method of allocation which
does not take account of the equitable considerations referred to above in this
Section 7(f). The amount paid or

                                       11
<PAGE>

payable by an indemnified party as a result of the losses, claims, damages or
liabilities (or actions or proceedings in respect thereof) referred to above in
this Section 7(f) shall be deemed to include any legal or other expenses
reasonably incurred by such indemnified party in connection with investigating
or defending any such action or claim. Notwithstanding the provisions of this
Section 7(f): (i) each Distributing Holder shall not be required to contribute
any amount in excess of the amount of proceeds received by such Holder from
sale(s) of such Holder's Shares pursuant to the Registration Statement or Demand
Registration Statement; and (ii) no person guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Act) shall be
entitled to contribution from any person who was not guilty of such fraudulent
misrepresentation.

         8. ADJUSTMENT OF EXERCISE PRICE. The Exercise Price in effect at the
time and the number and kind of securities purchasable upon the exercise of the
Warrant shall be subject to adjustment from time to time upon the happening of
certain events as follows:

                  (a) In case the Company shall (i) declare a dividend or make a
distribution on its outstanding shares of Common Stock in shares of Common
Stock, (ii) subdivide or reclassify its outstanding shares of Common Stock into
a greater number of shares, (iii) combine or reclassify its outstanding shares
of Common Stock into a smaller number of shares, or (iv) enter into any
transaction whereby the outstanding shares of Common Stock of the Company are at
any time changed into or exchanged for a different number or kind of shares or
other security of the Company or of another corporation through reorganization,
merger, consolidation, liquidation or recapitalization, then appropriate
adjustments in the number of Shares (or other securities for which such Shares
have previously been exchanged or converted) subject to this Placement Agent's
Warrant shall be made and the Exercise Price in effect at the time of the record
date for such dividend or distribution or of the effective date of such
subdivision, combination, reclassification, reorganization, merger,
consolidation, liquidation or recapitalization shall be proportionately adjusted
so that the Holder of this Placement Agent's Warrant exercised after such date
shall be entitled to receive the aggregate number and kind of shares of Common
Stock which, if this Placement Agent's Warrant had been exercised by such Holder
immediately prior to such date, the Holder would have been entitled to receive
upon such dividend, distribution, subdivision, combination, reclassification,
reorganization, merger, consolidation, liquidation or recapitalization. For
example, if the Company declares a 2 for 1 stock distribution and the Exercise
Price hereof immediately prior to such event was $7.00 per Share and the number
of Shares issuable upon exercise of this Placement Agent's Warrant was 85,500,
the adjusted Exercise Price immediately after such event would be $3.50 per
Share and the adjusted number of Shares issuable upon exercise of this Placement
Agent's Warrant would be 171,000. Such adjustment shall be made successively
whenever any event listed above shall occur.

                  (b) Whenever the Exercise Price is adjusted, as herein
provided, the Company shall promptly cause a notice setting forth the adjusted
Exercise Price and adjusted number of Shares issuable upon exercise of the
Placement Agent's Warrant to be mailed to the Holder, at its address set forth
herein, and shall cause a certified copy thereof to be mailed to the Company's
transfer agent, if any. The Company may retain a firm of independent certified
public accountants selected by the Board of Directors (who

                                       12
<PAGE>

may be the regular accountants employed by the Company) to make any computation
required by this Section 8, and a certificate signed by such firm shall be
conclusive evidence of the correctness of such adjustment.

                  (c) In the event that at any time, as a result of an
adjustment made pursuant to the provisions of this Section 8, the Holder of the
Placement Agent's Warrant thereafter shall become entitled to receive any shares
of the Company other than Common Stock, thereafter the number of such other
shares so receivable upon exercise of the Placement Agent's Warrant shall be
subject to adjustment from time to time in a manner and on terms as nearly
equivalent as practicable to the provisions with respect to the Common Stock
contained in Sections 8(a) above.

         9. GOVERNING LAW. This Agreement shall be governed by and in accordance
with the laws of the State of New York without regard to conflicts of laws
principles thereof.

         10. BINDING EFFECT ON SUCCESSORS. In case of any consolidation of the
Company with, or merger of the Company into, any other entity, or in case of any
sale or conveyance of all or substantially all of the assets of the Company
other than in connection with a plan of complete liquidation of the Company at
any time prior to the Expiration Date, then as a condition of such
consolidation, merger or sale or conveyance, the Company shall give written
notice of consolidation, merger, sale or conveyance to the Holder and, from and
after the effective date of such consolidation, merger, sale or conveyance the
Placement Agent's Warrant shall represent only the right to receive the
consideration that would have been issuable in respect of the Shares underlying
the Placement Agent's Warrant in such consolidation, merger, sale or conveyance
had the Placement Agent's Warrant been exercised in full immediately prior to
such effective time and the Holder shall have no further rights under this
Placement Agent's Warrant other than the right to receive such consideration.

         11. FRACTIONAL SHARES. No fractional shares shall be issued upon
exercise of this Placement Agent's Warrant. The Company shall, in lieu of
issuing any fractional share, pay the holder entitled to such fraction a sum in
cash equal to such fraction multiplied by the then effective Exercise Price.

         12. LOST WARRANTS. The Company represents and warrants to the Holder
hereof that upon receipt of evidence reasonably satisfactory to the Company of
the loss, theft, destruction, or mutilation of this Warrant and, in the case of
any such loss, theft or destruction, upon receipt of an indemnity reasonably
satisfactory to the Company, or in the case of any such mutilation upon
surrender and cancellation of such Warrant, the Company, at its expense, will
make and deliver a new Warrant, of like tenor, in lieu of the lost, stolen,
destroyed or mutilated Warrant.

         13. HEADINGS. The headings of the several sections and paragraphs of
this Warrant are inserted for convenience only and do not constitute a part of
this Warrant.

         14. MODIFICATION AND WAIVER. This Warrant and any provision hereof may
be changed, waived, discharged or terminated only by an instrument in writing
signed by the party against which enforcement of the same is sought.

                                       13
<PAGE>

         15. SURVIVAL. The rights and obligations of the Company, of the holder
of this Warrant and of the holder of Shares issued upon exercise of this Warrant
shall survive the exercise of this Warrant.

         IN WITNESS WHEREOF, the Company has caused this Placement Agent's
Warrant to be signed by its duly authorized officers under its corporate seal,
and this Placement Agent's Warrant to be dated July 28, 2003.

                                    NORTHFIELD LABORATORIES INC.

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

                                       14
<PAGE>

                                  PURCHASE FORM

                  (To be signed only upon exercise of Warrant)

         The undersigned, the holder of the foregoing Placement Agent's Warrant,
hereby irrevocably elects to exercise the purchase rights represented by such
Warrant for, and to purchase thereunder, _______________ Shares of Common Stock,
$0.01 par value per share (the "SHARES"), of NORTHFIELD LABORATORIES INC. and
either

[ ]      tenders herewith payment of the aggregate Exercise Price in respect of
the Shares in full, in the amount of $_________; or

[ ]      elects pursuant to Section 2(b) of such Warrant to convert such Warrant
into Common Stock on a cashless exercise basis; and

[ ]      requests that the certificates for the Shares issued in the name(s) of,
and delivered to _________________, whose address(es) is (are):

         Dated:   __________________________

                            By:
                                 ---------------------------

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

                                 ---------------------------
                                 Address

<PAGE>

                                  TRANSFER FORM

         (To be signed only upon transfer of Placement Agent's Warrant)

         For value received, the undersigned hereby sells, assigns, and
transfers unto ______________________________ the right to purchase Shares
represented by the foregoing Placement Agent's Warrant to the extent of
__________ Shares, and appoints _________________________ attorney to transfer
such rights on the books of Northfield Laboratories Inc., with full power of
substitution in the premises. The undersigned believes that each transferee is a
permitted transferee under Section 3 of the Placement Agent's Warrant.

         Dated:  ____________________________

                              By:
                                   -----------------------------

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

                                   -----------------------------
                                   Address

In the presence of:

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

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