Document:

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                                                                   EXHIBIT 10.28

                                    SUBLEASE

                  THIS SUBLEASE (the "Sublease") is made and entered into as of
the 31st day of July, 2002, by and between Cybear LC (the "Sublandlord"), whose
address is 5000 T-Rex Avenue, Suite 200, Boca Raton, Florida 33431, and
MyDocOnline, Inc. (the "Subtenant"), whose address is One Chisolm Trail, Suite
450, Round Rock, TX 78681.

                              W I T N E S S E T H:

         WHEREAS, that certain Lease Agreement dated September 14,1998 was
entered into by and between Blue Lake, Ltd., as landlord (the "Overlandlord"),
and Sublandlord, as tenant, as amended by First Amendment to Blue Lake Corporate
Center Standard Lease between Blue Lake, Ltd. and Cybear, Inc. dated as of
February 4, 1999 and Second Amendment to Blue Lake Corporate Center Standard
Lease between Blue Lake, Ltd. and Cybear, Inc. dated as of September 3, 1999
(collectively, (the "Overlease"), whereby Sublandlord leases from Overlandlord
approximately thirty-eight thousand sixty-eight (38,068) rentable square feet,
with an address of 5000 T-Rex Avenue, Suite 200, Boca Raton, Florida 33431 (the
"Premises"); and

         WHEREAS, Sublandlord has agreed to sublease to Subtenant that certain
portion of the Premises consisting of approximately Three Thousand Six Hundred
(3,600) square feet (the "Sublease Premises"), and Subtenant has agreed to
sublease the Sublease Premises from Sublandlord, on the terms and conditions
hereinafter set forth.

         NOW, THEREFORE, in consideration of the mutual covenants contained
herein and other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, Sublandlord and Subtenant hereby agree as
follows:

         1.       Incorporation of Recitals. The above recitals are true and
correct and are incorporated herein as if set forth in full.

         2.       Sublease. Sublandlord hereby subleases to Subtenant, and
Subtenant hereby subleases from Sublandlord, the Sublease Premises, a floor plan
of which is attached hereto and made a part hereof as Exhibit "A".

         3.       Overlease. Sublandlord and Subtenant agree that at all times
this Sublease is and shall be subject and subordinate to all of the terms,
covenants, conditions, and provisions of the Overlease. Subtenant hereby
acknowledges that it has received a copy of the Overlease and has examined and
approved same. All of the terms, covenants, conditions, and provisions of the
Overlease are incorporated herein by reference, and shall, as between
Sublandlord and Subtenant, constitute the terms, covenants, conditions, and
provisions of this Sublease, except to the extent that they are inapplicable to,
inconsistent with, or modified by the provisions of this Sublease. If either
Sublandlord or Subtenant receives any notice or demand from the Overlandlord
under the Overlease, the recipient shall promptly deliver a copy thereof to the
other party hereto. All defined terms in this Sublease shall have the same
meaning as in the Overlease, except if otherwise noted. Sublandlord and
Subtenant shall not do or permit to be done any act or thing which will
constitute a breach or violation of any of the terms, covenants, conditions, or
provisions of the Overlease.

         4.       Sublease Term. The term Of this Sublease (the "Sublease Term")
shall commence on the later of (a) the closing of that certain Asset Purchase
Agreement dated July___, 2002 (the "Closing") or (b) the date that Overlandlord
has provided the parties hereto with its consent to this Sublease (the
"Commencement Date"), and expiring two hundred forty (240) days from the Closing
(the "Expiration Date"), provided, however if Sublandlord is able to sublease or
assign the Premises, Sublandlord will provide Subtenant with a sixty (60) day
notice to vacate the Sublease Premises and Subtenant agrees to vacate the
Sublease Premises.

         5.       Rent. Subtenant shall pay to Sublandlord rent hereunder for
the Sublease Term (the " Rent") in the amount of Ten Thousand ($10,000.00)
Dollars in advance in equal monthly installments of Ten Thousand ($10,000.00)
Dollars, plus sales tax, on the first day of each month. At the Closing,
Subtenant shall pay to Sublandlord Twenty Thousand ($20,000.00) Dollars
representing the first and last months' Rent. The Rent for the Sublease Term
shall include the cost of furniture and equipment, utilities, common area
expenses, real estate taxes, telephone service and insurance.

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         6.       [DELETED].

         7.       Payments. If the period running from the Commencement Date to
the end of the first calendar month is less than a full calendar month, the
following month's Rent shall be appropriately apportioned. Rent, shall be paid
promptly when due, without notice or demand therefor, and without deduction,
abatement, counterclaim, or setoff of any amount or for any reason whatsoever.
Rent shall be paid to Sublandlord in lawful money of the United States of
America at the Sublandlord's address set forth in this Sublease or to such other
person, or at such address, or both, as Sublandlord may from time to time
designate by notice to Subtenant.

         8.       As-Is. Subtenant acknowledges and agrees that Sublandlord has
afforded Subtenant the opportunity for full and complete examination and
inspection of the Sublease Premises prior to executing this Sublease and that
Subtenant is accepting the Sublease Premises in "as-is" condition including
furniture, equipment and telephone service and that Sublandlord shall have no
obligation whatsoever to further furnish, render, or supply any money, work,
labor, fixture, material, decoration, or equipment in order to prepare the
Sublease Premises for Subtenant's occupancy. Any and all alterations and
improvements to the Sublease Premises shall be at Subtenant's expense and are
subject to (a) the prior written approval of Sublandlord and Overlandlord and
(b) the provisions of the Overlease regarding alterations and improvements.

         9.       Use. Subtenant shall use and occupy the Sublease Premises only
for such purposes as are permitted pursuant to the Overlease and for no other
purpose or purposes whatsoever.

         10.      Assignment and Subletting. Subtenant shall have no rights
whatsoever to assign this Sublease or sublet all or any portion of the Sublease
Premises

         11.      Insurance. Subtenant shall maintain, at Subtenant's sole cost
and expense, throughout the Sublease Term, the same insurance required to be
maintained by Sublandlord pursuant to Article 14 of the Overlease, with
Sublandlord and the Overlandlord named as additional insureds (as their
respective interests may appear), with limits of not less than those amounts
required pursuant to the Overlease. Subtenant shall deliver to Sublandlord and
Overlandlord a certificate of insurance evidencing the required coverages prior
to the Commencement Date. Subtenant shall procure and pay for renewals of such
insurance from tune to time before the expiration thereof and Subtenant shall
deliver in Sublandlord a certificate of such renewal policy at least thirty (30)
days prior to the expiration of any existing policy. All such policies shall be
issued in accordance with the requirements of the Overlease and shall, at a
minimum, be issued by companies of recognized responsibility licensed to do
business in the State of Florida and shall contain a provision whereby the same
cannot be cancelled or modified unless all additional insureds are given at
least thirty (30) days' prior written notice of such cancellation or
modification.

         12.      Casualty. In the event of any casualty of all or any portion
of the Sublease Premises, such casualty shall be governed by the applicable
provisions of the Overlease, including, without limitation, Article 17.

         13.      Condemnation. In the event of any condemnation of all or any
portion of the Sublease Premises, such condemnation shall be governed by the
applicable provisions of the Overlease, including, without limitation, Article
18.

         14.      Defaults. The rights and remedies of Sublandlord and Subtenant
hereunder shall be the same as the respective rights and remedies of
Overlandlord and Sublandlord under the Overlease, including, without limitation,
that the provisions for defaults by Subtenant and Sublandlord shall be as
provided in Article 23 of the Overlease. In addition, if Subtenant shall at any
time fail to make any payment or to perform any other obligation of Subtenant
hereunder, Sublandlord shall have the right, but not the obligation, upon five
(5) business days' notice to Subtenant, or without notice to Subtenant in the
Case of any circumstances that Sublandlord reasonably believes to be an
emergency, and without waiving or releasing Subtenant from any obligation of
Subtenant hereunder, to make such payment or perform such other obligation of
Subtenant in such manner and to such extent as Sublandlord shall deem necessary,
and, in exercising any such right, to pay any reasonable cost or expense, to
employ attorneys, and to incur and pay attorneys' fees and disbursements.
Subtenant shall pay to Sublandlord upon demand all sums so paid by Sublandlord
(including attorneys' fees and costs), together with interest thereon at an
annual rate equal to the then-maximum lawful interest rate, from the date of the
making of such expenditure.

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         15.      Subordination. This Sublease and all rights of Subtenant shall
be subject and subordinate to any and all mortgages, security agreements, or
like instruments resulting from any financing, refinancing, or collateral
financing (including renewals or extensions thereof), and to any and all ground
leases, made or arranged by Overlandlord and/or Sublandlord of its interests in
all or any part of the Sublease Premises, from time to time in existence,
whether now existing or hereafter created. Such subordination shall be
self-operative and shall not require any further instrument to evidence such
subordination. However, on request, Subtenant shall further evidence its
agreement to subordinate this Sublease to any and all documents and to all
advances made under such documents.

         16.      Estoppel Certificate. Subtenant shall be required to provide
estoppel certificates upon request by Sublandlord and/or Overlandlord in the
manner provided in Section 28 of the Overlease.

         17.      Parking. Commencing on the Commencement Date, Subtenant shall
have the right to utilize ten (10) unassigned parking spaces in the parking area
for the building out of Sublandlord's overall allotment of parking spaces, on
the terms and conditions set forth in Section 7 of the Overlease.

         18.      Notice. All notices required or permitted hereunder shall be
in writing and shall be served on Sublandlord, at the address set forth in the
preamble to this Sublease, and on Subtenant, prior to the Commencement-Date, at
the address set forth in the preamble to this Sublease, and after the
Commencement Date, at the Sublease Premises. Any such notices shall be either
(a) sent by certified mail, return receipt requested, or (b) sent by a
nationally recognized overnight courier, or (c) hand delivered with a courier's
receipt for delivery. Notices shall be deemed delivered on the day of receipt or
refusal of delivery. The above addresses may be changed by written notice to the
other party; provided, however, that no notice of a change of address shall be
effective until actual receipt of such notice.

         19.      Consents and Approvals. In any instance in which Sublandlord's
consent or approval is required under this Sublease, Sublandlord's refusal to
make or deliver such consent or approval shall be deemed reasonable if, inter
alia, such consent or approval has not been obtained from Overlandlord under the
Overlease, after request therefor by Sublandlord.

         20.      Waiver; Partial Invalidity. If either the Sublandlord or
Subtenant excuses or condones any default by the other of any obligation under
this Sublease, this shall not be a waiver of such obligation in respect of any
continuing or subsequent default and no such waiver shall be implied. If any
provision of this Sublease is held or rendered illegal or unenforceable it shall
be considered separate and severable from this Sublease and the remaining
provisions of this Sublease shall remain in force and bind the parties as though
the illegal or unenforceable provision had never been included in this Sublease.

         21.      Recording. Neither the Subtenant nor anyone claiming under the
Subtenant shall record this Sublease or any memorandum hereof in any public
records without the prior written consent of the Sublandlord and the
Overlandlord.

         21.      Successors. The rights and liabilities created by this
Sublease extend to and bind the successors and assigns of the Sublandlord and
the permitted successors and assigns of the Subtenant.

         22.      Captions and Section Numbers. The captions and section numbers
appearing in this Sublease are inserted only as a matter of convenience and in
no way affect the substance of this Sublease.

         23.      Extended Meanings. The words "hereof," "hereto," "hereunder"
and similar expressions used in this Sublease relate to the whole of this
Sublease and not only to the provisions in which such expressions appear. This
Sublease shall be read with all changes in number and gender as may be
appropriate or required by the context. Any reference to the Subtenant includes,
when the context allows, the employees, agents, invitees, and licensees of the
Subtenant and all others over whom the Subtenant might reasonably be expected to
exercise control. This Sublease has been fully reviewed and negotiated by each
party and their counsel and shall not be more strictly construed against either
party.

         24.      Entire Agreement; Governing Law; Time. This Sublease and its
Exhibits, if any, attached hereto are incorporated herein and set forth the
entire agreement between the Sublandlord and Subtenant concerning the Sublease
Premises and there are no other agreements or understandings between them. This
Sublease may not be modified except by

                                       -3-
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agreement in writing executed by the Sublandlord and Subtenant. This Sublease
shall be construed in accordance with and governed by the laws of the State of
Florida. Time is of the essence of this Sublease.

         25.      No Partnership. Nothing in this Sublease creates any
relationship between the parties other than that of sublessor and sublessee and
nothing in this Sublease constitutes the Sublandlord a partner of the Subtenant
or a joint venturer or member of a common enterprise with the Subtenant.

         26.      Brokerage. Sublandlord and Subtenant each represent and
warrant one to the other that neither of them has employed any broker in
connection with the negotiations of the terms of this Sublease or the execution
thereof. Sublandlord and Subtenant hereby agree to indemnify and to hold each
other harmless against any loss, expense, or liability with respect to any
claims for commissions or brokerage fees arising from or out of any breach of
the foregoing representation and warranty.

         27.      Security Deposit. As security for Subtenant's obligations
under this Sublease, simultaneously with its execution of this Sublease,
Subtenant shall deposit with Sublandlord the sum of N/A and __ /100
($_____________) Dollars (the "Security Deposit"). The Security Deposit shall be
held by Sublandlord without liability for interest and as security for the
performance by Subtenant of Subtenants covenants and obligations under this
Sublease, it being expressly understood that the Security Deposit shall not be
considered an advance payment of rental or a measure of Subtenant's liability
for damages in case of default by Subtenant. Sublandlord may commingle the
Security Deposit with Sublandlord's other funds. Sublandlord may, from time to
time, without prejudice to any other remedy, use the Security Deposit to the
extent necessary to make good any arrearages of rent or to satisfy any other
covenant or obligation of Subtenant hereunder. Following any such application of
the Security Deposit, Subtenant shall pay to Sublandlord on demand the amount so
applied in order to restore the Security Deposit to its original amount. If
Subtenant is not in default at the expiration or earlier termination of this
Sublease, and all of the repair and restoration obligations of Subtenant have
been fulfilled, then the balance of the Security Deposit remaining after any
such application shall be returned by Sublandlord to Subtenant. If Sublandlord
transfers its interest in the Premises during the Sublease Term of this
Sublease, Sublandlord may assign the Security Deposit to the transferee and
thereafter shall have no further liability for the return of such Security
Deposit.

         28.      No Options. Notwithstanding anything to the contrary contained
in this Sublease, if there are any provisions in the Overlease that pertain to
Sublandlord's rights regarding my option to renew the term of the Overlease, or
any option or right of refusal to expand the Sublease Premises, then such
provisions shall not be incorporated herein and Subtenant shall not have any
rights or benefits thereunder.

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         IN WITNESS WHEREOF, the parties hereto have executed this Sublease as
of the day and year first above written.

WITNESSES:                       SUBLANDLORD:

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

/s/ [ILLEGIBLE]                  By: /s/ Scott Lodin
--------------------------           -------------------------
                                 Name: Scott Lodin
/s/ [ILLEGIBLE]                  Title: President of ANDA, Inc., its Sole Member
--------------------------

                                 SUBTENANT:

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

/s/ [ILLEGIBLE]                  By: /s/ KIRK R. SCHVELER
--------------------------           ------------------------------
/s/ [ILLEGIBLE]                  Name: KIRK R. SCHVELER
--------------------------       Title: CEO

                                       -5-<PAGE>

                                                                   EXHIBIT 10.32

        THIS SUBLEASE AMENDMENT AGREEMENT made the 17th day of July 2003

BETWEEN:

                    OPTIWAVE CORPORATION/CORPORATION OPTIWAVE

         (a Canadian corporation, hereinafter called the "Sublandlord")
         OF THE FIRST PART
AND:

                                 ZIX CORPORATION

         (a Texas, U.S.A. corporation, hereinafter called the "Tenant")
         OF THE SECOND PART

AND
                      WAIDT CONSTRUCTION & DEVELOPMENTS LTD
         (hereinafter called the "Landlord")
         OF THE THIRD PART

         WHEREAS by written Sublease dated August 1, 2002 ("Sublease"), a
Sublease Amendment Agreement dated September 30, 2002 ("First Amendment") and a
Sublease Amendment Agreement dated November 19, 2002 ("Second Amendment")
between the Sublandlord, the Tenant and the Landlord, the Tenant subleased space
on the ground and 3rd floor of a building located at 7 Capella Court, Nepean,
Ontario ("the Building"). Unless otherwise specified, all capitalized terms used
herein shall have the meanings assigned to them in the Sublease. All currency
references herein are in Canadian dollars.

         AND WHEREAS the Tenant and the Sublandlord have agreed to renew and
further amend the Sublease so as to continue to sublet to the Tenant, effective
September 1, 2003, the entire third floor of the Building as shown on the floor
plan attached hereto and marked as Exhibit A and incorporated herein by
reference (the "Third Floor Leased Premises").

         AND WHEREAS the Landlord has agreed to renew and amend the Sublease
upon the following terms and conditions.

         NOW THEREFORE in consideration of the rents, covenants and conditions
herein reserved and contained, the parties agree as follows:

     1.  Except for the amendments expressly set out herein, the parties confirm
         that all other terms and conditions contained in the Sublease remain in
         full force and effect. More specifically, if the Sublease is not
         renewed pursuant to its terms, the Tenant shall vacate the Third Floor
         Leased Premises by August 31, 2005.

     2.  The Gross Rent payable by the Tenant pursuant to the Sublease shall
         remain $25,000.00 per month plus GST for July 2003 and August 2003 as
         set forth in the Second Amendment. Thereafter, (for the 24 month period
         September 1, 2003 to August 31, 2005) the Gross Rent payable by the
         Tenant will be decreased by $3,000.00 per month, plus GST, (to
         $22,000.00 per month plus GST) as payment for the Tenant's possession
         and occupation of the Third Floor Leased Premises. If the Sublease is
         renewed on the basis of Option One, the monthly Gross Rent payable
         shall be $30,000.00 plus GST for the duration of any such renewal term.
         If the Sublease is renewed on the basis of Option Two, the monthly
         Gross Rent payable shall be $27,000.00 plus GST for the duration of the
         one (1) year renewal term. Such amounts are detailed on Exhibit B.
         Terms of payment shall remain the same as specified in the Sublease.

     3.  The Third Floor Leased Premises are sublet to the Tenant in an "as is"
         condition with no requirement for any additional fit up, alterations,
         provision of furniture or equipment, use of

                                                   SUBLANDLORD  LANDLORD  TENANT

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         maintenance resources or leasehold improvements. There are no
         inducements offered to the Tenant and no free services will be provided
         in connection with the Tenant's occupation of the Third Floor Leased
         Premises. More specifically, the Tenant will continue not to receive
         the benefit of any phone system in connection with its occupation of
         the Third Floor Leased Premises and the Tenant will be required to
         purchase or lease, at its sole expense, a phone system that meets its
         requirements.

     4.  As previously amended in the Second Amendment, the common areas defined
         in the Sublease shall include the toilets and common hallways on the
         third floor. The second floor is not a common area.

     5.  GROSS RENT: For greater certainty, Tenant shall pay directly to the
         Landlord all gross rents, prepayments and deposits to be applied to the
         Sublandlord's rental account, as Gross Rent for the Third Floor Leased
         Premises, payable in equal monthly installments in advance on the first
         day of each calendar month during the term of the Sublease.

         IN WITNESS WHEREOF, the parties have executed this Sublease Amendment
         Agreement, under seal, as of the date written above.

         I, the undersigned Tenant, agree to and accept the above amendments.

SIGNED, SEALED AND DELIVERED  ) ZIX CORPORATION
in the presence of:           )
                              )
                              )
/s/ Carole Ann Rodgers        ) Per: /s/Wael Mohamed
----------------------              --------------------------------------------
Witness                       ) Print Name: Wael Mohamed
                              ) Title: VP, Global Sale     August 01/03
                              ) I/We have the authority to bind the corporation.

I, the undersigned Sublandlord, agree to and accept the above amendments.

SIGNED, SEALED AND DELIVERED  ) OPTIWAVE CORPORATION/CORPORATION OPTIWAVE
in the presence of:           )
                              )
                              )
/s/ Curtis Flanagan           ) Per: /s/ Chris Boland
-------------------                 --------------------------------------------
Witness                       ) Print Name: Chris Boland
                              ) Title: VP Finance
                              ) I/We have the authority to bind the corporation.

                                                   SUBLANDLORD  LANDLORD  TENANT

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I, the undersigned Landlord, agree to and accept the above amendments.

SIGNED, SEALED AND DELIVERED  ) WAIDT CONSTRUCTION & DEVELOPMENTS LTD.
in the presence of:           )
                              )
                              )
                              ) Per: /s/ Chris Moore
__________________________          --------------------------------------------
Witness                       ) Print Name: Chris Moore
                              ) Title: Officer
                              ) I/We have the authority to bind the corporation.

                                                   SUBLANDLORD  LANDLORD  TENANT

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