<PAGE>

                                                                    EXHIBIT 10.1

                                                  OPEN PORT TECHNOLOGY, INC.


                       1995 INCENTIVE STOCK OPTION PLAN


1.    Purpose
      -------

  The purpose of the Plan is to benefit the Company and its shareholders by
having the Company offer certain Employees a favorable opportunity to acquire
shares of Stock over a period of years, thereby giving such Employees a
permanent stake in the growth and prosperity of the Company, encouraging such
Employees to continue their service with the Company, and motivating such
Employees to devote their best efforts to the business and profitability of the
Company.  The Plan is not intended to qualify as an "employee stock purchase
plan" within the meaning of Code Section 423.

2.    Definitions
      -----------

  As used herein, the following definitions shall apply.

     2.1.    "Board" shall mean the Board of Directors of the Company, or a
committee appointed by the Board to perform all or some of the Board's duties
under this Plan.

     2.2.    "Code" shall mean the Internal Revenue Code of 1986, as amended.

     2.3.    "Company" shall mean Open Port Technology, Inc., an Illinois
corporation.
<PAGE>

     2.4.    "Date of Grant" shall mean the day and year written in the Option
Agreement relating to such Option.  The Date of Grant for an Option granted to
an Employee may be any date on or after the Employee's first day of employment
with the Company even if such date is prior to the effective date of this Plan.

     2.5.    "Director" shall mean any duly elected and qualified member of the
Board.

     2.6.    "Disability" shall mean any medically determinable physical or
mental impairment that, in the opinion of the Board, based upon medical reports
and other evidence satisfactory to the Board, can reasonably be expected to
prevent an Employee from performing substantially all of his customary duties of
employment for a continuous period of not less than twelve (12) months.

     2.7.    "Employee" shall mean any salaried employee of the Company.

     2.8.    "Exercise Price" shall mean the purchase price for shares of Stock
purchased pursuant to the exercise or partial exercise of an Option.

     2.9.    "Fair Market Value" shall mean, with respect to the valuation of
any shares of Stock, (i) if the Stock is publicly traded, the closing price of
the Stock on the trading day immediately preceding the business day during which
the shares of Stock are to be valued pursuant hereto, and (ii) if the Stock is
not publicly traded, the fair market value of the shares of Stock as reasonably
determined by the Board consistent with past practice.

     2.10.   "IPO" shall mean the closing of an initial public offering of the
common stock of the Company registered under the Securities Act.

                                       2
<PAGE>

     2.11.   "Option" shall mean any right to purchase Stock which has been
granted by the Board pursuant to the Plan.

     2.12.   "Option Agreement" shall mean an agreement executed by an officer
of the Company and an Employee evidencing the grant of an Option.

     2.13.   "Option Shares" shall mean the shares of Stock transferred pursuant
to the exercise of an Option.

     2.14.   "Optionee" shall mean any Employee who receives an Option pursuant
to the Plan.

     2.15.   "Plan" shall mean the Open Port Technology, Inc. 1995 Incentive
Stock Option Plan.

     2.16.   "Securities Act" shall mean the Securities Act of 1933, as amended.

     2.17.   "Stock" shall mean the no par value common stock of the Company.

3.    Shares Subject to the Plan
      --------------------------

  Except as provided in Section 4(a) hereof, the aggregate amount of Stock for
which Options may be granted shall not exceed 803,213 shares less (at the time
of the grant of any Option) all shares subject to any option granted under the
Open Port Technology, Inc. 1995 Non-Employee Stock Option Plan.

                                       3
<PAGE>

  Any shares subject to unexercised portions of Options which shall have
terminated, been canceled, or expired may again be made subject to Options.  In
addition, shares that have been repurchased by the Company may again be made
subject to Options.

4.    Adjustment
      ----------

     4.1.    The number of shares subject to the Plan and to Options shall be
adjusted as follows: (i) in the event that the number of shares of outstanding
Stock is changed by reason of a stock dividend, stock split, recapitalization or
combination of shares, the number of shares of Stock subject to the Plan and to
Options shall be proportionately adjusted; or (ii) in the event of any merger,
consolidation or reorganization of the Company with any other corporation or
corporations pursuant to which the holders of shares of Stock surrender shares
of Stock in exchange for other shares of stock or securities, there shall be
substituted for each share of Stock then subject to the Plan and to Options the
number and kind of shares of stock or other securities which the holders of
shares of Stock are entitled to receive for each share of Stock surrendered
pursuant to the transaction and the Exercise Price shall be proportionately
adjusted.

     4.2.    The number of shares subject to the Plan and Options shall not be
adjusted as a result of the issuance of shares of Stock by the Company (other
than an issuance described in subsection (a) of this Section 4), it being
understood that, upon such an issuance of shares of Stock, holders of Options
and holders of Option Shares will have a corresponding dilution of their
proportionate interests in the Stock.

                                       4
<PAGE>

5.    Administration of the Plan
      --------------------------

  The following provisions shall govern the administration of the Plan:

     5.1.    The Plan shall be administered by the Board.

     5.2.    The Board is authorized (but only to the extent not contrary to the
express provisions of the Plan) to interpret the Plan, to prescribe, amend and
rescind rules and regulations relating to the Plan and to the Options, to
determine the form and content of Options (except to the extent the form and
content of the Options are specified herein), and to make such other
determinations and exercise such other powers and authority as may be necessary
or advisable for the administration of the Plan.  Each Option granted shall be
evidenced by an Option Agreement in such form as may be determined by the Board.

     5.3.     A majority of the members of the Board eligible to act shall
constitute a quorum for purposes of acting with respect to the Plan, and the
action of a majority of the members present who are eligible to act at any
meeting at which a quorum is present shall be deemed the action of the Board.

     5.4.    All decisions, determinations and interpretations of the Board made
in good faith with respect to the Plan and Option Agreements shall be final and
conclusive on all persons affected thereby.

     5.5.    Neither the Board nor any member thereof shall be liable for any
act, omission, interpretation, construction or determination made in connection
with the Plan in good faith, and the members of the Board shall be entitled to
indemnification and reimbursement by the Company in respect of any claim, loss,
damage or expense (including counsel fees) arising therefrom to the full extent
permitted by law.

                                       5
<PAGE>

     5.6.    The aggregate fair market value of the Option Shares (determined as
of the Date of Grant) for which any Employee may be granted an Option or Options
which will first be exercisable in any single calendar year, taking account of
any special vesting provisions provided in an Option Agreement, may not exceed
$100,000.

6.    Eligibility
      -----------

  The Board is authorized to select Employees to receive Options depending on
the availability of shares of Stock for which Options may be granted pursuant to
the terms of the Plan.  In the event Options are granted pursuant to the Plan,
the Board is authorized to select the particular Employees who will receive such
Options and the number of shares of Stock under each such Option.  In granting
Options, the Board shall take into consideration the contribution an Employee
has made or may make to the success of the Company and such other factors as the
Board shall determine.  In no event shall any Employee or his or her legal
representatives, heirs, legatees, distributees or successors have any right to
participate in the Plan except to such extent, if any, as the Board shall
determine.  No Options will be granted to any Employee who owns stock
representing more than ten percent (10%) of the voting power of all classes of
stock of the Company or any parent or subsidiary corporation unless the Exercise
Price is at least one hundred ten percent (110%) of the Fair Market Value at the
Date of Grant.

7.    Term of the Plan
      ----------------

  The Plan shall continue in effect until terminated pursuant to Section 20
hereof; or until there is no more stock as to which an Option may be granted and
no Options are outstanding; provided, however, that all Options must be granted
within 10 years from the effective date of the Plan.

8.    Restrictions on Transfers
      -------------------------


     8.1.    The Options may not be transferred, assigned, pledged or
hypothecated in any way and will not be subject to execution, attachment or
similar process,

                                       6
<PAGE>

except as provided by this Plan and except by will or under the laws of descent
and distribution (subject to the repurchase option described in Section 18
hereof).

     8.2.    The Option Shares may not be transferred, assigned, pledged or
hypothecated, voluntarily, involuntarily or by operation of law, except as
provided by this Plan and any Option Agreement pertaining to such Options.

     8.3.    An Option will terminate immediately upon any attempted transfer,
assignment, pledge or hypothecation of such Option in violation of this Section
8, and any attempted transfer, assignment, pledge or hypothecation of any Option
Shares in violation of this Section 8 will be void without further action by the
Company and have no effect.

9.    Restrictions on Voting
      ----------------------

  Until the occurrence of an IPO, Option Shares will be voted by the then chief
executive officer of the Company, pursuant to irrevocable proxies in the form
attached hereto as Exhibit B, executed by the Optionee upon the exercise of an
Option.

10.    Vesting of Options
       ------------------

  Options are exercisable only upon and after vesting.  Except as provided in
Section 11 hereof and except as otherwise may be specifically provided in an
Option Agreement, Options shall vest according to the following schedule:

     10.1.  as to one-fifth (1/5) of the Option Shares on the first anniversary
of the Date of Grant;

                                       7
<PAGE>

     10.2.  as to an additional one-fifth (1/5) of the Option Shares on the
second anniversary of the Date of Grant; and

     10.3.  as to an additional one-fifth (1/5) of the Option Shares on the
third anniversary of the Date of Grant;

     10.4.  as to an additional one-fifth (1/5) of the Option Shares on the
fourth anniversary of the Date of Grant; and

     10.5.  as to the remaining one-fifth (1/5) of the Option Shares on the
fifth anniversary of the Date of Grant.

  The above vesting schedule assumes the Optionee's continuous employment with
the Company.  No Option or part thereof shall vest after the date the Optionee
ceases to be an Employee for any reason, and any unvested portion of an Option
theretofore held by such an Optionee shall terminate as of that date.

11.    Special Vesting Provisions
       --------------------------

  In the event of the proposed dissolution or liquidation of the Company, the
Option will terminate immediately prior to the consummation of such proposed
action, unless otherwise provided by the Board.  The Board may, in the exercise
of its sole discretion in such instances, declare that any Option shall
terminate as of a date fixed by the Board and give each Optionee the right to
exercise his or her Option as to all or any part of the Optioned Stock,
including Shares as to which the Option would not otherwise be exercisable.  In
the event of a proposed sale of all or substantially all of the assets of the
Company, or the merger of the Company with or into another corporation, the
Board may provide for the Optionee to have the right to exercise the Option as
to all of the Option Stock, including Shares as to which the Option would not
otherwise be exercisable.  The Board may notify the Optionee that the Option
shall be fully exercisable and the Option will terminate upon the consummation
of such sale or merger.

                                       8
<PAGE>

12.    When Options May Be Exercised
       -----------------------------

     12.1.    Except as provided in subsections (b) and (c) of this Section 12,
a vested Option or the vested portion of an Option, shall be exercised, if at
all, by the Optionee at any time before the tenth anniversary of its Date of
Grant.

     12.2.    If an Optionee ceases to be an Employee for any reason, such
Optionee's vested Options must be exercised, if at all, not later than thirty
(30) days following the date such Optionee ceases to be an Employee. Any
unvested portion of an Option shall terminate immediately upon the cessation of
employment of the Optionee holding the Option.

     12.3.    In the event of the occurrence of any of the events described in
Section 11 hereof and the adoption by the Board of a resolution providing for
the exercise of the rights provided to the Board under Section 11 hereof, the
vested Options shall not be exercisable after the occurrence of such event.  The
Company shall notify all Optionees of any such impending sale.  With respect to
any Optionee that desires to exercise the vested portion of his or her Option
prior to such event, the Company may instead pay such Optionee the excess of the
amount received or to be received for the Option Shares over the amount that
would have been received from such Optionee upon the exercise of the vested
portion of such Option.

     12.4.    Unless the Optionee desires to forego the benefit of the Option
being considered an incentive stock option under Section 422 of the Code, no
Option or any part thereof may be exercised by the Optionee while there is
outstanding any incentive stock option which was granted by the Company to the
Optionee at an earlier time.

13.    Exercise Price
       --------------

  The Exercise Price shall be $1.62 per share for Options granted on or before
the earlier of (i) the adoption by the Board of a resolution changing the
Exercise Price or (ii) an IPO.

                                       9
<PAGE>

At all times, when established, the Exercise Price shall be equal to or greater
than the Fair Market Value.

14.    Exercise of Option
       ------------------

  During the Optionee's lifetime, Options shall be exercisable only by the
Optionee or his legal representative or guardian.  Options shall not be
exercisable by the spouse of any Optionee during such Optionee's lifetime,
unless such spouse is acting in his or her capacity as the legal representative
or guardian of the Optionee.  In the event of the Optionee's death, the Option
shall be exercisable by the person or entity (including the Optionee's estate)
that has obtained the Optionee's rights under the Option by will or under the
laws of descent and distribution.

  Options shall be exercised if at all, by submitting to the Company (a) a
Notice of Exercise in the form attached hereto as Exhibit A, (b) the Irrevocable
Proxy, duly executed, (c) any other written representations, covenants, and
undertakings that the Company may prescribe pursuant to the Shareholders
Agreements or to satisfy securities laws and regulations or other requirements,
and (d) a certified or bank cashier's check payable to the order of the Company
in an amount equal to the full purchase price of the shares to be purchased.

  Upon receipt of the Notice of Exercise (subject to Sections 15, 16, and 17 of
this Agreement), the Company shall issue a new certificate or certificates to
the holder of the Option.  The certificate or certificates for the shares as to
which the Option shall have been exercised shall be registered in the name of
the holder of the Option and shall be delivered to or upon the written order of
the holder of the Option.  The shares shall bear a legend substantially in the
following form:

     "THE SHARES SUBJECT TO THIS CERTIFICATE ARE SUBJECT TO
     TRANSFER AND VOTING RESTRICTIONS SET FORTH IN THE OPEN PORT
     TECHNOLOGY, INC. 1995 INCENTIVE STOCK OPTION PLAN (THE
     "PLAN"). COPIES OF THE PLAN ARE ON FILE IN THE OFFICE OF THE
     SECRETARY OF THE CORPORATION. BY ACCEPTING THE SHARES OF
     STOCK EVIDENCED BY THIS CERTIFICATE, THE HOLDER AGREES TO BE
     BOUND BY THE PLAN AS IT MAY BE AMENDED FROM TIME TO TIME."

                                       10
<PAGE>

15.    Securities Law Restrictions
       ---------------------------

  The Company shall not be obligated to issue any stock certificates evidencing
a transfer upon exercise of an Option, until, in the opinion of the Company and
its counsel, such transfer and issuance of stock certificates will not involve
any violation of applicable federal and state securities laws, the rules and
regulations promulgated thereunder, and the requirements of any stock exchange
upon which the Stock may then be listed.  Acceptance of an Option by an Optionee
shall constitute the Optionee's agreement (binding on any person who succeeds to
the Optionee's rights and obligations under the Option Agreement by reason of
the Optionee's death) that, if the Stock is not publicly traded as of the date
the Option is exercised, any shares of Stock purchased upon the exercise of the
Option shall be acquired for the Optionee's own account and not with a view to
distribution and that each notice of the exercise of any portion of the Option
shall be accompanied by a written representation and covenant signed by the
Optionee, in such form as may be specified by the Company, confirming such
agreement and containing such other provisions as may be prescribed by the
Company.  The Company may, at its election, release an Optionee from the
Optionee's agreement to take for the Optionee's own account and not with a view
to distribution of the shares of Stock purchased upon exercise of an Option if,
in the opinion of the Company, such covenant ceases to be necessary for
compliance with the applicable federal and state securities laws (including the
rules and regulations promulgated thereunder) and the requirements of any stock
exchange upon which the Stock may then be listed.

  If the shares purchased upon exercise of an Option are not covered by an
effective registration statement under the Securities Act, the Company may place
the following legend (or a legend which is substantially similar to the
following legend) upon, and issue appropriate stock transfer instructions with
respect to, the certificate or certificates representing the shares transferred
upon exercise of the Option:

     "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
     REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
     "SECURITIES ACT"), OR ANY APPLICABLE STATE SECURITIES LAWS
     (THE STATE LAWS"), AND SUCH SHARES MAY NOT BE TRANSFERRED
     UNLESS (A) A REGISTRATION STATEMENT UNDER THE SECURITIES ACT
     AND APPLICABLE STATE LAWS COVERING SUCH TRANSFER IS THEN IN
     EFFECT; OR (B) AN OPINION OF COUNSEL, SATISFACTORY TO THE
     CORPORATION, HAS BEEN FURNISHED STATING THAT SUCH

                                       11
<PAGE>

     TRANSFER IS EXEMPT FROM THE REGISTRATION REQUIREMENTS OF THE
     SECURITIES ACT AND APPLICABLE STATE LAWS."

16.    Listing or Registration of Stock
       --------------------------------

  Each Option is subject to the requirement that, if at any time the Board shall
determine, in its discretion, that the listing, registration or qualification of
the shares of Stock subject to the Option upon any securities exchange or under
any state or federal law, or the consent or approval of any government
regulatory body, is necessary or desirable as a condition of, or in connection
with, the granting or exercise of the Option or the issuance or purchase of
shares under the Option, the Option may not be exercised in whole or in part
until such listing, registration, qualification, consent or approval shall have
been effected or obtained free of any conditions not acceptable to the Board.
The Company shall be under no obligation to effect or obtain any such listing,
registration, qualification, consent or approval if the Board shall determine,
in its discretion, that such action would not be in the best interests of the
Company.  The Company shall not be liable for damages due to a delay in the
delivery or issuance of any stock certificates for any reason whatsoever,
including, but not limited to, a delay caused by listing, registration or
qualification of the shares of Stock subject to an Option under any securities
exchange or under any federal or state law, or by the effecting or obtaining of
any consent or approval of any governmental body with respect to the granting or
exercise of the Option or the issue or purchase of shares under the Option.

17.    Withholding of Taxes
       --------------------

  The Board may make such provisions and take such steps as it may deem
necessary or appropriate for the withholding of any taxes which the Company is
required by any law or regulation of any governmental authority, whether
federal, state or local, domestic or foreign, to withhold in connection with any
Option, including, but not limited to, the withholding of the issuance of all or
any portion of the shares of Stock subject to the Option until the holder of the
Option reimburses the Company for the amount required to be withheld with
respect to such taxes, canceling any portion of the issuance of the shares of
Stock subject to the Option in an amount sufficient to reimburse the Company for
such amount, deducting from the Optionee's wages an amount sufficient to
reimburse the Company for such amount, or taking any other action reasonably
required to satisfy the withholding obligation of the Company.

                                       12
<PAGE>

18.    Repurchase Option
       -----------------

  The Options and Option Shares are subject to the rights of the Company to
repurchase or acquire the Option Shares upon the occurrence of certain events,
including but not limited to: death or disability of the Optionee; cessation of
employment with the Company for any reason; or a transfer of the Option or
Option Shares, voluntarily, involuntarily or by operation of law.  The terms of
this repurchase option with respect to Option Shares shall be set forth in the
Option Agreement pertaining to such Options.

19.    Modification of Options
       -----------------------

  At any time and from time to time the Board may provide for the modification,
extension, or renewal of any outstanding Option, provided that no such
modification, extension or renewal shall impair the Option in any respect
without the consent of the holder of the Option.

20.    Amendment and Termination of the Plan
       -------------------------------------

  The Board may provide for the alteration, suspension or discontinuation of the
Plan, except that no such action may increase the benefits accruing to Employees
under the Plan, increase (other than as provided in Section 4(a) hereof) the
maximum number of shares permitted to be issued upon the exercise of Options, or
materially modify the requirements as to eligibility for participation in the
Plan unless such action is subject to approval by the shareholders of the
Company.

21.    Shareholder Rights
       ------------------

  A holder of an Option shall have none of the rights of a shareholder with
respect to the shares of Stock subject to the Option until the transfer of such
shares to him or her has been duly recorded on the stock transfer books of the
Company upon the exercise of the Option.

                                       13
<PAGE>

22.    Continued Employment Not Presumed
       ---------------------------------

  Nothing in the Plan or any document describing it nor the grant of an Option
shall give any Optionee the right to continue in employment with the Company or
affect the right of the Company to terminate the employment of any Optionee with
or without cause.

                                       14
<PAGE>

23.    Effective Date
       --------------

  The foregoing Open Port Technology, Inc. 1995 Incentive Stock Option Plan is
hereby adopted by the Company as of October 19, 1995.



                                   Open Port Technology, Inc.


                                        /s/ Randy S. Storch
                                   By:  ------------------------------

                                        Randy S. Storch, President

                                       15
<PAGE>

                                   EXHIBIT A

                                      TO

                          OPEN PORT TECHNOLOGY, INC.

                       1995 INCENTIVE STOCK OPTION PLAN


                              NOTICE OF EXERCISE


               (to be executed only upon exercise of the Option)


  Reference is made to the Open Port Technology, Inc. 1995 Incentive Stock
Option Agreement, dated as of ___________________ _____, 1995 (the "Option
Agreement"), between Open Port Technology, Inc., an Illinois corporation (the
"Company"), and  _____________________________________ (the "Optionee").
Capitalized terms used herein and not otherwise defined have the meanings
assigned to such terms in the Option Agreement.

     23.1.    The Optionee hereby irrevocably exercises the option for and
purchases _______________ shares of Stock.

     23.2.    The full purchase price for the shares of Stock being purchased
hereunder, calculated in accordance with the Option Agreement, is
$_______________, and the Optionee is delivering to the Company simultaneously
with the delivery of this Notice of Exercise a certified or bank cashier's check
payable to the order of the Company in such amount.

     23.3.    The shares of Stock being purchased hereunder are being acquired
for the Optionee's own account and not with a view to distribution thereof in
violation of applicable Federal or state securities laws.
<PAGE>

     23.4.    The Optionee requests that certificates for the shares of Stock
being purchased hereunder be issued in the name of and delivered to the Optionee
at the following address:


                           _________________________
                           _________________________
                           _________________________
                           _________________________

                                       2
<PAGE>

     Dated as of ____________________    ______________________________

                                         (Signature)


                                         ______________________________

                                         (Name)


                                         ______________________________

                                         (Signature of Spouse)


                                         ______________________________

                                         (Name)

                                       3
<PAGE>

                                   EXHIBIT B

                                      TO

                  OPEN PORT TECHNOLOGY, INC. (the "Company")

                 1995 INCENTIVE STOCK OPTION PLAN (the "Plan")


                               IRREVOCABLE PROXY


  The undersigned hereby revokes any previous proxies and irrevocably appoints
Randy S. Storch (the "Proxyholder") and his successor, pursuant to the Plan as
the proxy of the undersigned to attend any and all meetings of the shareholders
of the Company, and any adjournments or postponements of such meetings
(collectively, a "Meeting"), to vote for and in the name, place and stead of the
undersigned at any Meeting all shares of common stock, no par value per share
(the "Stock"), owned by the undersigned on the date of this proxy and any other
shares of Stock hereafter acquired by the undersigned (collectively, the "Proxy
Shares"), to execute written consents to corporate action, and to represent and
otherwise act for the undersigned on any and all matters with the same force and
effect as if the undersigned were personally present at such meeting or were
executing such consent.

  This proxy is coupled with an interest and is expressly made irrevocable and
will be effective until the earliest to occur of (i) the consummation of an
initial public offering by the Company that is registered under the Securities
Act of 1933, as amended or (ii) the expiration of ten (10) years from the
execution date hereof.  The undersigned acknowledges that monetary damages would
be an inadequate remedy for a breach of the provisions of this proxy and that
(in addition to any other remedy available at law) the obligations of the
undersigned and the rights of the Proxyholder are specifically enforceable.

  The undersigned authorizes the Proxyholder to substitute any other person or
entity to act under this proxy, to revoke any such substitution, and to file
this proxy and any substitution or revocation of this proxy with the Secretary
of the Company.

     Dated as of ____________________      ______________________________

                                           (Signature)

                                       4
<PAGE>

                                        ______________________________

                                        (Name)


                                        ______________________________

                                        (Signature of Spouse)


                                        ______________________________

                                        (Name)

                                       5
<PAGE>

                             AMENDMENT NUMBER ONE

                                      TO

                          OPEN PORT TECHNOLOGY, INC.

                       1995 INCENTIVE STOCK OPTION PLAN

     1.  Reference to Plan
         -----------------

     Reference is hereby made to that certain Open Port Technology, Inc. 1995
Incentive Stock Option Plan; as used herein, the term "Plan" shall refer to the
Plan as modified by this Amendment.  The terms used herein which are defined in
the Plan shall have the meanings provided for in the Plan, unless otherwise
defined herein.  Except as expressly modified hereby, all of the terms and
provisions of the Plan shall continue in full force and effect.  A copy of this
Amendment shall be attached to and made a part of the Plan.

     2.  Amendment to Section 2(g) of the Plan
         ---------------------------- --------

     Section 2(g) of the Plan is hereby amended so as to read in its entirety as
follows:

          (g) "Employee" shall mean any salaried employee of the Company or of
     any "Parent" or "Subsidiary" of the Company (as such terms are defined in
     Section 424 of the Code); any references to employment with the Company,
     shall be deemed to include the Company and any Parent or Subsidiary of the
     Company, as the context may require.

     3.  Effective Date
         --------------

     This Amendment to the Plan is hereby adopted by the Committee as of the 1st
day of February, 1996.

                                                      Open Port Technology, Inc.
<PAGE>

                             AMENDMENT NUMBER TWO

                                      TO

                          OPEN PORT TECHNOLOGY, INC.

                       1995 INCENTIVE STOCK OPTION PLAN

     1.  Reference to Plan
         -----------------

         Reference is hereby made to that certain Open Port Technology, Inc.
1995 Incentive Stock Option Plan, as amended by Amendment Number One to the Open
Port Technology, Inc. 1995 Incentive Stock Option Plan dated as of February 1,
1996; as used herein, the term "Plan" shall refer to the Plan as modified by
Amendment Number One and by this Amendment. The terms used herein which are
defined in the Plan shall have the meanings provided for in the Plan, unless
otherwise defined herein. Except as expressly modified hereby, all of the terms
and provisions of the Plan shall continue in full force and effect. A copy of
this Amendment shall be attached to and made a part of the Plan.

     2.  Amendment to Section 2(q) of the Plan
         -------------------------------------

         Section 2(q) of the Plan is hereby amended so as to read in its
entirety as follows:

               (q)  "Stock" shall mean the common stock, par value $.001 per
         share, of the Company.

     3.  Amendment to Section 10 of the Plan
         -----------------------------------

         Section 10 of the Plan is hereby amended so as to read in its entirety
as follows:
<PAGE>

                    Options are exercisable only upon and after vesting. Except
          as provided in Section 11 hereof and except as otherwise may be
          specifically authorized by the Board and provided in an Option
          Agreement, Options shall vest according to the following schedule:

               (a)  as to one-fourth (1/4th) of the Option Shares, on the first
                    anniversary of the Date of Grant; and

               (b)  as to an additional one-thirty-sixth (1/36th) of the Option
                    Shares, on the same calendar month day as the Date of Grant
                    occurring in each of the thirty-six (36) calendar months
                    occurring after the first anniversary of the Date of Grant.

                    The above vesting schedule assumes the Optionee's continuous
          employment with the Company. No Option or part thereof shall vest
          after the date the Optionee ceases to be an Employee for any reason,
          and any unvested portion of an Option theretofore held by such an
          Optionee shall terminate as of that date.

     4.  Effective Date
         --------------

         This Amendment to the Plan is hereby adopted by the Board as of the
30th day of April, 1996.

                                            Open Port Technology, Inc.

                                       2

<PAGE>

                            AMENDMENT NUMBER THREE

                                      TO

                          OPEN PORT TECHNOLOGY, INC.

                       1995 INCENTIVE STOCK OPTION PLAN


     1.  Reference to Plan
         -----------------

     Reference is hereby made to that certain Open Port Technology, Inc. 1995
Incentive Stock Option Plan, as amended by Amendment Number One to the Open Port
Technology, Inc. 1995 Incentive Stock Option Plan, dated as of February 1, 1996,
and Amendment Number Two to Open Port Technology, Inc. 1995 Incentive Stock
Option Plan.  As used herein, the term "Plan" shall refer to the Open Port
Technology, Inc 1995 Incentive Stock Option Plan as modified by Amendment Number
One, Amendment Number Two, and by this Amendment Number Three.  The terms used
herein which are defined in the Plan shall have the meanings provided for in the
Plan, unless otherwise defined herein.  Except as expressly modified hereby, all
of the terms and provisions of the Plan shall continue in full force and effect.
A copy of this Amendment Number Three shall be attached to and made a part of
the Plan.

     2.  Amendment to Section 3 of the Plan
         ----------------------------------

     The first paragraph of Section 3 of the Plan is hereby amended so as to
read in its entirety as follows:

          Except as provided in Section 4(a) hereof, the aggregate amount of
     Stock for which Options may be granted shall not exceed 3,682,695 shares
     (based on the capitalization of the Company existing as of January 1, 1997)
     less (at the time of the grant of any Option) all shares subject to any
     option granted under the Option Port Technology, Inc. 1995 Non-Employee
     Stock Option Plan, as amended.

     3.  Effective Date
         --------------
<PAGE>

     This Amendment Number Three to the Plan is hereby adopted by the Board as
of February 6, 1997 and approved by the shareholders of the Company as of
February 11, 1997.


                                                  Open Port Technology, Inc.

                                       2

<PAGE>

                             AMENDMENT NUMBER FOUR
                                      TO
                          OPEN PORT TECHNOLOGY, INC.
                       1995 INCENTIVE STOCK OPTION PLAN


24.  Reference to Plan
     -----------------

     Reference is hereby made to that certain Open Port Technology, Inc. 1995
Incentive Stock Option Plan, as amended by Amendment Number One to the Open Port
Technology, Inc. 1995 Incentive Stock Option Plan, dated as of February 1, 1996,
Amendment Number Two to Open Port Technology, Inc. 1995 Incentive Stock Option
Plan, dated as of April 30, 1996, and Amendment Number Three to Open Port
Technology Stock Option Plan, dated as of February 11, 1997.  As used herein,
the term "Plan" shall refer to the Open Port Technology, Inc. 1995 Incentive
Stock Option Plan as modified by Amendment Number One, Amendment Number Two,
Amendment Number Three and by this Amendment Number Four.  The terms used herein
which are defined in the Plan shall have the meanings provided for in the Plan,
unless otherwise defined herein.  Except as expressly modified hereby, all of
the terms and provisions of the Plan shall continue in full force and effect.  A
copy of this Amendment Number Four shall be attached to and made a part of the
Plan.

25.  Amendment to Section 2 of the Plan
     ----------------------------------

     Section 2 of the Plan is hereby amended by adding the following new
paragraph (r) at the end thereof:

          (r)  "Change of Control Event" shall mean, and be deemed to have
               occurred:  (i) upon the acquisition at any time (excluding any
               acquisition in connection with any public offering of equity
               securities of the Company pursuant to a registration statement
               filed under the Securities Act) by a "person" or "group" (as used
               in Sections 13(d) and 14(d)(2) of the Securities Exchange Act of
               1934, as amended (the "Exchange Act")) (excluding, for this
               purpose, the Company or any Subsidiary or any employee benefit
               plan of the Company or any Subsidiary) of the beneficial
               ownership (as defined in Rule 13d-3 promulgated under the
               Exchange Act), directly or indirectly, of securities representing
               fifty percent (50%) or more of the combined voting power of the
               then-outstanding securities of the Company; or (ii) in the event
               that the Board or the shareholders of the Company shall approve a
               merger, share exchange (other than a merger or share exchange
               with a wholly-owned subsidiary), consolidation, or sale or other
               disposition of substantially all of the assets of the Company, as
               a
<PAGE>

               result of which immediately following such transaction the
               shareholders of the Company shall not hold, directly or
               indirectly, a majority of the voting power of the then-
               outstanding securities of: (A) in the case of a merger or
               consolidation, the surviving or resulting corporation; (B) in the
               case of a share exchange, the acquiring corporation; or (C) in
               the case of a sale or other disposition of substantially all of
               the assets, each surviving, resulting or acquiring corporation
               which, immediately following the transaction, holds fifty percent
               (50%) or more of the assets of the Company.

26.  Amendment of Section 11 of the Plan
     -----------------------------------

     Section 11 of the Plan is hereby amended by adding the following new
paragraph at the end of thereof:

          Further, notwithstanding anything to the contrary in Section 10 or
     this Section 11, upon the occurrence of a Change of Control Event, with
     respect to each Option, if three (3) years has not elapsed since the Date
     of Grant, then the vesting of the Option shall be accelerated so that any
     portion of the Option that would have vested within three (3) years from
     the Date of Grant, shall automatically vest as of the date of the Change of
     Control Event.  The remaining unvested portion shall continue to vest
     according to above schedule (as if three (3) years had elapsed since the
     Date of Grant).

27.  Amendment of Section 18 of the Plan
     ------------------------------------
     Section 18 of the Plan is hereby amended so as to read in its entirety as
follows:

          The Options and the Option Shares are subject to the rights of the
     Company to repurchase or acquire the Option Shares upon the occurrence of
     certain events, including but not limited to:  a transfer of the Option or
     Option Shares, voluntarily, involuntarily or by operation of law or
     cessation of employment with the Company for any reason, but excluding in
     any instance upon the occurrence of a Change of Control Event.  The terms
     of this repurchase option with respect to Option Shares shall be set forth
     in the Option Agreement pertaining to such Options.

28.  Effective Date
     --------------
     This Amendment Number Four to the Plan is hereby adopted by the Board as of
the 20th day of November, 1997.

                                                  Open Port Technology, Inc.

                                       2

<PAGE>

                             AMENDMENT NUMBER FIVE
                                      TO
                          OPEN PORT TECHNOLOGY, INC.
                       1995 INCENTIVE STOCK OPTION PLAN


29.  Reference to Plan
     -----------------

     Reference is hereby made to that certain Open Port Technology, Inc. 1995
Incentive Stock Option Plan, as amended by Amendment Number One to the Open Port
Technology, Inc. 1995 Incentive Stock Option Plan, dated as of February 1, 1996,
Amendment Number Two to Open Port Technology, Inc. 1995 Incentive Stock Option
Plan, dated as of April 30, 1996, Amendment Number Three to Open Port Technology
Stock Option Plan, dated as of February 11, 1997, and Amendment Number Four to
Open Port Technology Stock Option Plan, dated as of November 20, 1997.  As used
herein, the term "Plan" shall refer to the Open Port Technology, Inc. 1995
Incentive Stock Option Plan as modified by Amendment Number One, Amendment
Number Two, Amendment Number Three, Amendment Number Four, and this Amendment
Number Five.  The terms used herein which are defined in the Plan shall have the
meanings provided for in the Plan, unless otherwise defined herein.  Except as
expressly modified hereby, all of the terms and provisions of the Plan shall
continue in full force and effect.  A copy of this Amendment Number Five shall
be attached to and made a part of the Plan.

30.  Amendment to Section 3 of the Plan
     ----------------------------------

     The first paragraph of Section 3 of the Plan is hereby amended so as to
read in its entirety as follows:

          Except as provided in Section 4(a) hereof, the aggregate amount of
     Stock for which Options may be granted shall not exceed 4,432,695 shares
     (based on the capitalization of the Company existing as of January 1, 1997)
     less (at the time of the grant of any Option) all shares subject to any
     option granted under the Open Port Technology, Inc. 1995 Non-Employee Stock
     Option Plan, as amended.

31.  Effective Date
     --------------

     This Amendment Number Five to the Plan is hereby adopted by the Board as of
the 23rd day of April, 1998 and approved by the Shareholders of the Company as
of June 15, 1998.

                                                  Open Port Technology, Inc.
<PAGE>

                             AMENDMENT NUMBER SIX
                                      TO
                          OPEN PORT TECHNOLOGY, INC.
                       1995 INCENTIVE STOCK OPTION PLAN


32.  Reference to Plan
     -----------------

     Reference is hereby made to that certain Open Port Technology, Inc. 1995
Incentive Stock Option Plan, as amended by Amendment Number One to the Open Port
Technology, Inc. 1995 Incentive Stock Option Plan, dated as of February 1, 1996,
Amendment Number Two to Open Port Technology, Inc. 1995 Incentive Stock Option
Plan, dated as of April 30, 1996, Amendment Number Three to Open Port Technology
Stock Option Plan, dated as of February 11, 1997, Amendment Number Four to Open
Port Technology Stock Option Plan, dated as of November 20, 1997, and Amendment
Number Five to Open Port Technology Stock Option Plan, dated as of June 15,
1998.  As used herein, the term "Plan" shall refer to the Open Port Technology,
Inc. 1995 Incentive Stock Option Plan as modified by the foregoing Amendments
and this Amendment Number Six.  The terms used herein which are defined in the
Plan shall have the meanings provided for in the Plan, unless otherwise defined
herein.  Except as expressly modified hereby, all of the terms and provisions of
the Plan shall continue in full force and effect.  A copy of this Amendment
Number Six shall be attached to and made a part of the Plan.

33.  Amendment to Section 14 of the Plan
     -----------------------------------

     The second paragraph of Section 14 of the Plan is hereby amended so as to
read in its entirety as follows:

          Options shall be exercised if at all, by submitting to the Company (a)
     a Notice of Exercise in the form attached hereto as Exhibit A, (b) the
     Irrevocable Proxy, duly executed, (c) any other written representations,
     covenants, and undertakings that the Company may prescribe pursuant to the
     Shareholders Agreements or to satisfy securities laws and regulations or
     other requirements, and (d) a certified or bank cashier's check payable to
     the order of the Company, or any other form of payment determined to be
     acceptable by the Board, in its sole discretion, in an amount equal to the
     full purchase price of the shares to be purchased.

34.  Amendment to Exhibit A to the Plan
     ----------------------------------

     Paragraph (b) of Exhibit A to the Plan is hereby amended so as to read in
its entirety as follows:

          (b) The full purchase price for the shares of Stock being purchased
     hereunder, calculated in accordance with the Option Agreement, is
     $____________, and the Optionee is delivering to the Company simultaneously
<PAGE>

     with the delivery of this Notice of Exercise a certified or bank
     cashier's check payable to the order of the Company in such amount,
     or any other form of payment determined to be acceptable by the
     Board, in its sole discretion.

35.  Effective Date
     --------------

     This Amendment Number Six to the Plan is hereby adopted by the Board as of
the 31st day of July, 1998.

                                          Open Port Technology, Inc.

                                       2

<PAGE>

                           AMENDMENT NUMBER SEVEN TO
                          OPEN PORT TECHNOLOGY, INC.
                       1995 INCENTIVE STOCK OPTION PLAN


36.  Reference to Plan
     -----------------

     Reference is hereby made to that certain Open Port Technology, Inc. 1995
Incentive Stock Option Plan (the "Plan"), as amended by Amendment Number One to
the Plan, dated as of February 1, 1996, Amendment Number Two to the Plan, dated
as of April 30, 1996, Amendment Number Three to the Plan, dated as of February
11, 1997, Amendment Number Four to the Plan, dated as of November 20, 1997,
Amendment Number Five to the Plan, dated as of June 15, 1998 and Amendment
Number Six to the Plan, dated as of July 31, 1998.  As used herein, the term
"Plan" shall refer to the Open Port Technology, Inc. 1995 Incentive Stock Option
Plan as modified by Amendment Number One, Amendment Number Two, Amendment Number
Three, Amendment Number Four, Amendment Number Five, Amendment Number Six and
this Amendment Number Seven.  The terms used herein which are defined in the
Plan shall have the meanings provided for in the Plan, unless otherwise defined
herein.  Except as expressly modified hereby, all of the terms and provisions of
the Plan shall continue in full force and effect.  A copy of this Amendment
Number Seven shall be attached to and made a part of the Plan.

37.  Amendment to Section 3 of the Plan
     ----------------------------------
     The first paragraph of Section 3 of the Plan is hereby amended so as to
read in its entirety as follows:

          Except as provided in Section 4(a) hereof, the aggregate amount
     of Stock for which Options may be granted shall not exceed 5,432,695
     shares (based on the capitalization of the Company existing as of
     January 1, 1997) less (at the time of the grant of any Option) all
     shares subject to any option granted under the Open Port Technology,
     Inc. 1995 Non-Employee Stock Option Plan, as amended.

38.  Effective Date
     --------------
     This Amendment Number Seven to the Plan is hereby adopted by the Board as
of October 29, 1998 and approved by the Shareholders of the Company as of
February 8, 1999.


                                             Open Port Technology, Inc.
<PAGE>

                           AMENDMENT NUMBER EIGHT TO
                          OPEN PORT TECHNOLOGY, INC.
                       1995 INCENTIVE STOCK OPTION PLAN


39.  Reference to Plan
     -----------------

     Reference is hereby made to that certain Open Port Technology, Inc. 1995
Incentive Stock Option Plan (the "Plan"), as amended by Amendment Number One to
the Plan, dated as of February 1, 1996, Amendment Number Two to the Plan, dated
as of April 30, 1996, Amendment Number Three to the Plan, dated as of February
11, 1997, Amendment Number Four to the Plan, dated as of November 20, 1997,
Amendment Number Five to the Plan, dated as of June 15, 1998, Amendment Number
Six to the Plan, dated as of July 31, 1998, and Amendment Number Seven to the
Plan, dated as of February 8, 1999.  As used herein, the term "Plan" shall refer
to the Open Port Technology, Inc. 1995 Incentive Stock Option Plan as modified
by Amendment Number One, Amendment Number Two, Amendment Number Three, Amendment
Number Four, Amendment Number Five, Amendment Number Six, Amendment Number Seven
and this Amendment Number Eight.  The terms used herein which are defined in the
Plan shall have the meanings provided for in the Plan, unless otherwise defined
herein.  Except as expressly modified hereby, all of the terms and provisions of
the Plan shall continue in full force and effect.  A copy of this Amendment
Number Eight shall be attached to and made a part of the Plan.

40.  Amendment to Section 3 of the Plan
     ----------------------------------
     The first paragraph of Section 3 of the Plan is hereby amended so as to
read in its entirety as follows:

          Except as provided in Section 4(a) hereof, the aggregate amount
     of Stock for which Options may be granted shall not exceed 8,432,695
     shares (based on the capitalization of the Company existing as of
     January 1, 1997) less (at the time of the grant of any Option) all
     shares subject to any option granted under the Open Port Technology,
     Inc. 1995 Non-Employee Stock Option Plan, as amended.

41.  Effective Date
     --------------
     This Amendment Number Eight to the Plan is hereby adopted by the Board as
of January 27, 2000 and approved by the Shareholders of the Company as of
November, 1999.


                                             Open Port Technology, Inc.
<PAGE>

                           AMENDMENT NUMBER NINE TO
                          OPEN PORT TECHNOLOGY, INC.
                       1995 INCENTIVE STOCK OPTION PLAN


42.  Reference to Plan
     -----------------

     Reference is hereby made to that certain Open Port Technology, Inc. 1995
Incentive Stock Option Plan (the "Plan"), as amended by Amendment Number One to
the Plan, dated as of February 1, 1996, Amendment Number Two to the Plan, dated
as of April 30, 1996, Amendment Number Three to the Plan, dated as of February
11, 1997, Amendment Number Four to the Plan, dated as of November 20, 1997,
Amendment Number Five to the Plan, dated as of June 15, 1998, Amendment Number
Six to the Plan, dated as of July 31, 1998, Amendment Number Seven to the Plan,
dated as of February 8, 1999 and Amendment Number Eight to the Plan, dated as of
January 27, 2000.  As used herein, the term "Plan" shall refer to the Open Port
Technology, Inc. 1995 Incentive Stock Option Plan as modified by Amendment
Number One, Amendment Number Two, Amendment Number Three, Amendment Number Four,
Amendment Number Five, Amendment Number Six, Amendment Number Seven, Amendment
Number Eight and this Amendment Number Nine.  The terms used herein which are
defined in the Plan shall have the meanings provided for in the Plan, unless
otherwise defined herein.  Except as expressly modified hereby, all of the terms
and provisions of the Plan shall continue in full force and effect.  A copy of
this Amendment Number Nine shall be attached to and made a part of the Plan.

43.  Amendment to Section 3 of the Plan
     ----------------------------------

     The first paragraph of Section 3 of the Plan is hereby amended so as to
read in its entirety as follows:

          Except as provided in Section 4(a) hereof, the aggregate amount
     of Stock for which Options may be granted shall not exceed 9,732,695
     shares (based on the capitalization of the Company existing as of
     January 1, 1997) less (at the time of the grant of any Option) all
     shares subject to any option granted under the Open Port Technology,
     Inc. 1995 Non-Employee Stock Option Plan, as amended.

44.  Effective Date
     --------------

     This Amendment Number Nine to the Plan is hereby adopted by the Board as of
March 24, 2000 and approved by the Shareholders of the Company as of March 24,
2000.


                                             Open Port Technology, Inc.
<PAGE>

                            AMENDMENT NUMBER TEN TO
                           OPEN PORT TECHNOLOGY, INC
                       1995 INCENTIVE STOCK OPTION PLAN


1.   Reference to Plan
     -----------------

     Reference is hereby made to that certain Open Port Technology, Inc. 1995
Incentive Stock Option Plan (the "Plan"), as amended by Amendment Number One to
the Plan, dated as of February 1, 1996, Amendment Number Two to the Plan, dated
as of April 30, 1996, Amendment Number Three to the Plan, dated as of February
11, 1997, Amendment Number Four to the Plan, dated as of November 20, 1997,
Amendment Number Five to the Plan, dated as of June 15, 1998, Amendment Number
Six to the Plan, dated as of July 31, 1998, Amendment Number Seven to the Plan,
dated as of February 8, 1999, Amendment Number Eight to the Plan, dated as of
January 27, 2000, and Amendment Number Nine to the Plan, dated as of March 24,
2000. As used herein, the term "Plan" shall refer to the Open Port Technology,
Inc. 1995 Incentive Stock Option Plan as modified by Amendment Number One,
Amendment Number Two, Amendment Number Three, Amendment Number Four, Amendment
Number Five, Amendment Number Six, Amendment Number Seven, and Amendment Number
Eight and Amendment Number Nine. The terms used herein which are defined in the
Plan shall have the meanings provided for in the Plan, unless otherwise defined
herein. Except as expressly modified hereby, all of the terms and provisions of
the Plan shall continue in full force and effect. A copy of this Amendment
Number Ten shall be attached to and made part of the Plan.

2.   Amendments to Section 2 of the Plan
     -----------------------------------

     Section 2 of the Plan is hereby amended by amending paragraph (l) so as to
read in its entirety as follows:

          (l)  "Option Agreement" shall mean an agreement executed by an officer
     of the Company and an Employee evidencing the grant of an Option, as it may
     be amended, modified, extended or renewed from time to time, subject to
     Section 19.

     Section 2 of the Plan is hereby further amended by amending paragraph (r)
so as to read in its entirety as follows:

     (r)  "Change of Control Event" means, unless otherwise defined for a
          particular Optionee in an Option Agreement or in an employment
          agreement between the Company and such Optionee which addresses the
          effect of a Change of Control Event (as therein defined) on benefits
          hereunder, shall mean, and be deemed to have occurred:

          (i)  upon the acquisition at any time (excluding any acquisition in
               connection with any public offering of equity securities of the
               Company pursuant to a registration statement filed under the
               Securities Act) by a person or group (as used in Sections 13(d)
               and 14(d)(2) of the Securities Exchange Act of
<PAGE>

               1934, as amended (the "Exchange Act"), excluding for this
               purpose, the Company or any Subsidiary or any employee benefit
               plan of the Company or any Subsidiary) of the beneficial
               ownership (as defined in Rule 13d-3 promulgated under the
               Exchange Act), directly or indirectly, of securities representing
               fifty percent (50%) or more of the combined voting power of the
               then-outstanding securities of the Company; except that no Change
               of Control shall be deemed to have occurred solely by reason of
               such beneficial ownership (A) by a corporation of which fifty
               percent (50%) or more of the beneficial ownership is then held,
               directly or indirectly, in substantially the same proportions by
               the persons who held the beneficial ownership of the Company
               immediately before such acquisition, or (B) resulting directly
               from an issuance of Stock by the Company to such person; or

          (ii) the approval by the Board or the shareholders of the Company of a
               merger, share exchange (other than a merger or share exchange
               with a wholly-owned subsidiary), consolidation, reorganization,
               or similar transaction, or a plan or agreement for the sale or
               other disposition of all or substantially all of the consolidated
               assets of the Company or a plan of liquidation of the Company, as
               a result of which immediately following such transaction the
               shareholders of the Company shall not hold, directly or
               indirectly, a majority of the voting power of the then-
               outstanding securities of the surviving, resulting or acquiring
               corporation (or in the case of a sale or other disposition of
               assets, of each surviving, resulting or acquiring corporation
               which immediately after the transaction holds fifty percent (50%)
               of the former assets of the Company).

3.   Amendment to Section 7 of the Plan
     ----------------------------------

     Section 7 of the Plan is hereby amended so as to read in its entirety as
follows:

          The Plan shall continue in effect until terminated pursuant to Section
     20 hereof, or until there is no more Stock as to which an Option may be
     granted and no Options are outstanding; provided, however, that all Options
     must be granted within 10 years from the effective date of the Plan, and no
     Options shall be granted under the Plan after an IPO.

4.   Amendments to Section 8 of the Plan
     -----------------------------------

     Section 8 of the Plan is hereby amended so as to read in its entirety as
follows:

          (a)  The Options may not be transferred, assigned, pledged or
     hypothecated in any way and will not be subject to execution, attachment or
     similar process, except as provided by this Plan and except by will or
     under the laws of descent and distribution, or pursuant to a domestic
     relations order issued by a court of competent jurisdiction, or by
     designation of beneficiary pursuant to subsection (c) of this Section 8,
     and except as may

                                       2
<PAGE>

     be permitted by an Option Agreement in accordance with subsection (d) of
     this Section 8, and subject to the repurchase option described in Section
     18 hereof.

          (b)  Prior to an IPO the Option Shares may not be transferred,
     assigned, pledged or hypothecated, voluntarily or involuntarily or by
     operation of law, except as provided by this Plan and any Option Agreement
     pertaining to such Options.

          (c)  Each Optionee under the Plan may, from time to time, name any
     beneficiary or beneficiaries (who may be an individual or a trust and who
     may be named contingently or successively) to exercise on such
     beneficiary's behalf any Options that are outstanding and exercisable after
     the death of the Optionee. Each such designation shall revoke all prior
     designations by the same Optionee, shall be in a form prescribed by the
     Company, and will be effective only when filed by the Optionee in writing
     with the Company during the Optionee's lifetime. In the absence of any such
     designation, the Option to the extent outstanding and exercisable after the
     death of an Optionee may be exercised by his or her executors,
     administrators, legatees or distributees of his or her estate as determined
     under his or her will or by the laws of descent and distribution. If an
     Option is exercised by the executors, administrators, legatees or
     distributees of the estate of a deceased Optionee or by the guardian or
     legal representative of a Optionee, the Company shall be under no
     obligation to issue Stock thereunder unless and until it is satisfied that
     the person or persons exercising the Option are the duly appointed
     beneficiary or legal representatives of the Optionee or of the deceased
     Optionee's estate or the proper legatees or distributees of such estate.

          (d)  If the Option Agreement so provides and the Optionee consents to
     foregoing the benefits of the Option being considered an incentive stock
     option under Section 422 of the Code, then notwithstanding subsection (a)
     above, an Optionee may transfer an Option in the manner prescribed by the
     Board, and subject to such terms and conditions as may be prescribed by the
     Board, to any Permissible Transferee (as defined below). For purposes of
     this Plan, "Permissible Transferee" means any member of the Immediate
                 ----------------------
     Family (as defined below) of the Optionee to whom such Option was granted,
     any trust the primary beneficiaries of which consist exclusively of the
     Optionee or members of the Optionee's Immediate Family or any corporation,
     partnership or similar entity, the owners of which consist exclusively of
     the Optionee or members of the Optionee's Immediate Family. For purposes of
     this Section, "Immediate Family" means such Optionee's spouse, children,
                    ----------------
     nieces, nephews, grandchildren, great grandchildren, stepchildren, parents,
     stepparents, grandparents, siblings, half siblings, and the spouses of such
     individuals.

          (e)  An Option will terminate immediately upon any attempted transfer,
     assignment, pledge or hypothecation of such Option in violation of this
     Section 8, and any attempted transfer, assignment, pledge or hypothecation
     of any Option Shares in violation of this Section 8 will be void without
     further action by the Company and have no effect.

5.   Amendment to Section 11 of the Plan
     -----------------------------------

                                       3
<PAGE>

     The last paragraph of Section 11 of the Plan is hereby amended so as to
read in its entirety as follows:

          Further, notwithstanding anything to the contrary in Section 10 or
     this Section 11, but subject to any different provision for a particular
     Optionee in an Option Agreement or in an employment agreement between the
     Company and such Optionee which addresses the effect of a Change in Control
     Event (as therein defined) on benefits hereunder, upon the occurrence of a
     Change in Control Event, with respect to each Option, if three (3) years
     has not elapsed since the Date of Grant, then the vesting of the Option
     shall be accelerated so that any portion of the Option that would have
     vested within three (3) years from the Date of Grant shall automatically
     vest as of the date of the Change of Control Event. The remaining unvested
     portion shall continue to vest according to the above schedule (as if three
     (3) years had elapsed since the Date of Grant).

6.   Amendments to Section 12 of the Plan
     ------------------------------------

     Section 12(b) of the Plan is hereby amended so as to read in its entirety
as follows:

          (b)  Unless otherwise provided for a particular Optionee in an Option
     Agreement and which may distinguish among reasons for termination of
     employment, (i) any unvested portion of an Option shall terminate
     immediately upon the cessation of employment for any reason of the Optionee
     holding the Option, and (ii) if an Optionee ceases to be an Employee for
     any reason, such Optionee's vested Options must be exercised, if at all,
     not later than thirty (30) days following the date such Optionee ceases to
     be an Employee.

     Section 12(d) of the Plan is hereby deleted.

7.   Amendment to Section 14 of the Plan
     -----------------------------------

     Section 14 of the Plan is hereby amended so as to read in its entirety as
follows:

          Except to the extent provided in an Option Agreement which permits
     transfer of Options pursuant to Section 8(d), during the Optionee's
     lifetime Options shall be exercisable only by the Optionee or his legal
     representative or guardian. Options shall not be exercisable by the spouse
     of any Optionee during such Optionee's lifetime, unless such spouse is
     acting in his or her capacity as the legal representative or guardian or a
     permissible transferee under such Option Agreement, of the Optionee. In the
     event of the Optionee's death, the Option shall be exercisable by the
     person or entity (including the Optionee's estate) that has obtained the
     Optionee's rights under the Option by designation of beneficiary, by will
     or under the laws of descent and distribution, or by such permitted
     transfer.

          Options shall be exercised, if at all, by submitting to the Company
     (a) a Notice of Exercise in the form attached hereto as Exhibit A, (b) if
     exercise occurs prior to an IPO, the Irrevocable Proxy, duly executed, (c)
     any other written representations, covenants and undertakings that the
     Company may prescribe pursuant to any shareholders agreements or

                                       4
<PAGE>

     to satisfy securities laws and regulations or other requirements, and (d)
     full payment for the Option Stock made by cash, personal check or wire
     transfer or, subject to the approval of the Board, any one or more of the
     following means:

               (i)  Shares of Stock that have been held by the Optionee for at
          least six months or purchased by the Optionee on the open market
          ("Mature Shares"), valued at their Fair Market Value on the date of
          exercise;

               (ii) pursuant to procedures approved by the Board, through the
          sale of the Stock acquired on exercise of the Option through a broker-
          dealer to whom the Optionee has submitted an irrevocable notice of
          exercise and irrevocable instructions to deliver promptly to the
          Company the amount of sale or loan proceeds sufficient to pay for such
          Stock, together with, if requested by the Company, the amount of
          federal, state, local or foreign withholding taxes payable by Optionee
          by reason of such exercise.

     If Mature Shares are used to pay the Exercise Price, then if requested by
     the Secretary or Assistant Secretary of the Company, the Optionee shall
     deliver to the Secretary or Assistant Secretary the agreement evidencing
     the Option and the Optionee's certificate that such shares have been held
     by the Optionee for at least six months or were purchased on the open
     market and such certificate shall identify the number of shares of Stock
     and the stock certificate or other document or notation which evidences
     such stock ownership.  The number of Mature Shares being so used and the
     number of shares of Stock purchased upon exercise may be evidenced by a
     notation on the agreement and the agreement shall be returned to the
     Optionee.  No fractional shares of Stock (or cash in lieu of fractional
     shares) shall be issued upon exercise of an Option and the number of shares
     of Stock that may be purchased upon exercise shall be rounded to the
     nearest number of whole shares.

          Upon receipt of the Notice of Exercise (subject to Sections 15, 16 and
     17 of this Plan), the Company shall issue a new certificate of certificates
     to the holder of the Option. The certificate or certificates for the shares
     as to which the Option shall have been exercised shall be registered in the
     name of the holder of the Option and shall be delivered to or upon the
     written order of the holder of the Option. If the shares are issued before
     an IPO the shares shall bear a legend in substantially the following form:

          "THE SHARES SUBJECT TO THIS CERTIFICATE ARE SUBJECT TO TRANSFER AND
          VOTING RESTRICTIONS SET FORTH IN THE OPEN PORT TECHNOLOGY, INC. 1995
          INCENTIVE STOCK OPTION PLAN (THE "PLAN"). COPIES OF THE PLAN ARE ON
          FILE IN THE OFFICE OF THE SECRETARY OF THE CORPORATION.  BY ACCEPTING
          THE SHARES OF STOCK EVIDENCED BY THIS CERTIFICATE, THE HOLDER AGREES
          TO BE BOUND BY THE PLAN AS IT MAY BE AMENDED FROM TIME TO TIME."

          Whenever under the Plan, shares are to be delivered upon exercise of
     an Option the Company shall be entitled to require (x) that the Optionee
     remit an amount in cash, or

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<PAGE>

     if determined by the Board, Mature Shares, sufficient to satisfy all
     federal, state, local and foreign tax withholding requirements related
     thereto ("Required Withholding"), (y) the withholding of such Required
     Withholding from compensation otherwise due to the Optionee or from any
     shares due to the Optionee under the Plan or (z) any combination of the
     foregoing.

          Any Optionee who makes a disposition not described in Section
     422(a)(i) of the Code of Option Shares acquired under an incentive stock
     option shall remit to the Company an amount sufficient to satisfy all
     resulting Required Withholding; provided that, in lieu of or in addition to
     the foregoing, the Company shall have the right to withhold such Required
     Withholding from compensation otherwise due to the Optionee or from any
     shares or other payment due to the Optionee under the Plan.

8.   Amendments to Section 18 of the Plan
     ------------------------------------

     Section 18 of the Plan is hereby amended to read in its entirety as
follows:

          The Options and the Option Shares are subject to the rights of the
     Company to repurchase or acquire the Option Shares upon the occurrence of
     certain events, including but not limited to: a transfer of the Option or
     Option Shares, voluntarily, involuntarily or by operation of law or
     cessation of employment with the Company for any reason, but excluding in
     any instance upon the occurrence of a Change of Control Event or after an
     IPO. The terms of this repurchase option with respect to the Option Shares
     shall be set forth in the Option Agreement pertaining to such Options.

9.   Amendments to Section 20 of the Plan
     ------------------------------------

     Section 20 is amended to read as follows:

          The Board may provide for the alteration, suspension or
     discontinuation of the Plan, except that no such action may increase (other
     than as provided in Section 4(a) hereof) the maximum number of shares
     permitted to be issued upon the exercise of Options, or materially modify
     the requirements as to eligibility for participation in the Plan, unless
     such action is subject to approval by the shareholders of the Company.

10.  Effective Date
     --------------

     This Amendment Number Ten to the Plan is hereby adopted by the Board as of
April 3, 2000 subject to approval by the Shareholders of the Company.

                                             Open Port Technology, Inc.

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