Document:

<PAGE>

                                                                    Exhibit 10.5

                           OPEN PORT TECHNOLOGY, INC.

                       2000 EMPLOYEE STOCK PURCHASE PLAN

<PAGE>

                     OPEN PORT TECHNOLOGY, INC CORPORATION
                       2000 EMPLOYEE STOCK PURCHASE PLAN

                         I. Purpose and Effective Date
                            --------------------------

1.1  The purpose of the Open Port Technology, Inc. 2000 Employee Stock Purchase
     Plan (the "Plan") is to provide an opportunity for eligible employees to
     acquire a proprietary interest in the Open Port Technology, Inc. (the
     "Company") through the purchase of shares of common stock of the Company.

1.2  The Company intends the Plan to qualify as an "employee stock purchase
     plan" under Section 423 of the Internal Revenue Code of 1986, as amended
     (the "Code"). The Plan shall be construed in a manner consistent with the
     requirements of Section 423 of the Code.

1.3  The Plan shall be effective upon approval of the Company's stockholders.
     No option shall be granted under the Plan after the earliest of (i) the day
     before the tenth (10th) annual anniversary of the date on which the Plan is
     approved by the Board, or (ii) the date on which the Plan is terminated by
     the Board in accordance with Section 12.6 of the Plan.

                                II. Definitions
                                    -----------

     The following words and phrases, when used in this Plan, unless their
     context clearly indicates otherwise, shall have the following respective
     meanings:

2.1  "Base Earnings" means all compensation received by a Participant from the
     Company or a Participating Subsidiary, including salary deferrals by the
     Participant under Sections 401(k) and 125 of the Code, bonuses and overtime
     pay, but excluding short-term disability, long-term disability or workers
     compensation payments and similar amounts.

2.2  "Board"  has the meaning prescribed for that term in Section 1.3.

2.3  "Code"  has the meaning prescribed for that term in Section 1.1.

2.4  "Committee" means the committee of the Board appointed pursuant to Section
     3.1.

2.5  "Common Stock" means the Company's common stock, $.001 par value.

2.6  "Company" has the meaning prescribed for that term in Section 1.1.

2.7  "Cut-Off Date" means the date established by the Committee from time to
     time by which enrollment forms must be received prior to an Enrollment
     Date.

2.8  "Effective Date" means the date described in Section 1.3.
<PAGE>

2.9   "Eligible Employee" means an Employee eligible to participate in the Plan
      in accordance with Article V.

2.10  "Employee" means an individual who performs services for the Company or a
      Participating Subsidiary pursuant to an employment relationship described
      in Treasury Regulations Section 31.3401(c)-1 or any successor provision.

2.11  "Enrollment Date" means for any Employee who has completed the service
      requirement for participation in the Plan prior to the first trading day
      of an Enrollment Period, the first trading day of such Enrollment Period.

2.12  "Enrollment Period" means, as to the Company or a Participating
      Subsidiary, a period of six months or such other duration not in excess of
      27 months as shall be established from time to time by the Committee with
      respect to the Employees of the Company or such Participating Subsidiary,
      as applicable. Each Enrollment Period shall commence on a date specified
      by the Committee. Enrollment Periods and the commencement dates for
      Enrollment Periods may, but need not, be different for the Company and
      each Participating Subsidiary. Unless otherwise specified by the
      Committee, the initial Enrollment Period shall be the six-month period
      commencing on the first day of the calendar quarter that begins at least
      30 days after the IPO Date. Succeeding Enrollment Periods shall, unless
      otherwise specified by the Committee, be six-month periods beginning on
      each successive semiannual anniversary of the first day of the initial
      Enrollment Period.

2.13  "Exchange Act" means the Securities Exchange Act of 1934.

2.14  "Fair Market Value" of any security of the Company means, as of any
      applicable date:

      (a)  if the security is listed for trading on the New York Stock Exchange,
           the closing price, regular way, of the security as reported on the
           New York Stock Exchange Composite Tape, or if no sale of the security
           shall have been reported for such date, on the next preceding date
           for which such a sale was reported; or

      (b)  if the security is not so listed, but is listed on another national
           securities exchange or authorized for quotation on the Nasdaq
           National Market, the closing price, regular way, of the security on
           such exchange or the Nasdaq National Market, as the case may be, or
           if no such sale of the security shall have been reported for such
           date, on the next preceding date for which such a sale was reported;

      (c)  if the security is not listed for trading on a national securities
           exchange or authorized for quotation on the Nasdaq National Market,
           the average of the closing bid and asked prices as reported by the
           Nasdaq SmallCap Market or, if no such prices shall have been so
           reported for such date, on the next preceding date for which such
           prices were so reported, or

      (d)  if the security is not listed for trading on a national securities
           exchange and is not authorized for quotation on the Nasdaq National
           Market or the Nasdaq Small Cap

                                      -2-
<PAGE>

          Market, the fair market value of the security as determined in good
          faith by the Committee.

2.15  "Grant Date" means a date on which an Eligible Employee is granted options
      under the Plan.

2.16  "including" means "including without limitation".

2.17  "IPO" means the initial public offering of Common Stock as contemplated in
      the registration statement on Form S-1 filed by the Company with the SEC
      on April 5, 2000, and as subsequently amended.

2.18  "IPO Date" means the closing date under the underwriting agreement between
      the Company and the underwriters of the IPO with respect to Firm Shares
      (as defined in the underwriting agreement).

2.19  "Participant" means an Eligible Employee who has enrolled in the Plan
      pursuant to Article VI.

2.20  "Participating Subsidiary" means a Subsidiary which has been designated by
      the Committee in accordance with Section 3.3(e) as covered by the Plan.

2.21  "Purchase Date" means the specific trading day during an Enrollment Period
      as may be established by the Committee from time to time prior to the
      beginning of the Enrollment Period for all options to be granted during
      such Enrollment Period on which shares of Common Stock are purchased in
      accordance with Article IX of the Plan. Unless otherwise specified by the
      Committee, the Purchase Date for each Enrollment Period shall be the last
      day of such Enrollment Period, or, if such day is not a trading day, the
      next day that is a trading day.

2.22  "Rule 16b-3" means Rule 16b-3 promulgated by the SEC under the Exchange
      Act.

2.23  "SEC" means the Securities and Exchange Commission.

2.24  "Securities Act" means the Securities Act of 1933.

2.25  "Subsidiary" means any corporation in an unbroken chain of corporations
      beginning with the Company, if as of the applicable Enrollment Date, each
      of the corporations other than the last corporation in the chain owns
      stock representing 50% or more of the total combined voting power of all
      classes of stock in one of the other corporations in the chain.

                              III. Administration
                                   --------------

3.1   The Plan shall be administered by the Compensation Committee of the Board
      which shall consist of not less than two persons who are directors of the
      Company. Membership on the Committee shall be subject to such limitations
      as the Board deems appropriate to

                                      -3-
<PAGE>

      permit transactions in Common Stock pursuant to the Plan to be exempt from
      liability under Section 16(b) of the Exchange Act pursuant to Rule 16b-3
      of the SEC thereunder.

3.2   The Committee may select one of its members as chairman and may appoint a
      secretary. The Committee shall make such rules and regulations for the
      conduct of its business as it shall deem advisable; provided, however,
      that all determinations of the Committee shall be made by a majority of
      its members.

3.3   The Committee shall have the power, subject to the express provisions of
      the Plan:

      (a)  to determine from time to time the time or times when options shall
           be granted;

      (b)  to construe and interpret the Plan and options granted under it, and
           to establish, amend and revoke rules for its administration;

      (c)  to correct any defect, or supply any omission, or reconcile any
           inconsistency in the Plan, in a manner and to the extent it shall
           deem necessary or appropriate to carry out the intent of the Plan;

      (d)  to prescribe the terms and provisions for participation in the Plan;

      (e)  to designate from time to time which Subsidiaries of the Company
           shall be Participating Subsidiaries; and

      (f)  to determine all questions of policy and expediency that may arise in
           the administration of the Plan, and, generally, to exercise such
           powers and perform such acts as are deemed necessary or expedient to
           promote the best interests of the Company.

3.4   This Article III relating to the administration of the Plan may be amended
      by the Board from time to time as may be desirable to satisfy any
      requirements of or under the federal securities and/or other applicable
      laws of the United States, or to obtain any exemption under such laws.

                             IV. Number of Shares
                                 ----------------

4.1   480,000 shares of Common Stock are reserved for sales and authorized for
      delivery pursuant to the Plan. The number of shares of Common Stock
      reserved shall increase as of each May 1, beginning May 1, 2001, by a
      number of shares of Common Stock equal to the lesser of (a) one percent of
      the number of shares of Common Stock outstanding as of the close of
      business on such date, or (b) 266,667 shares of Common Stock. Subject to
      the foregoing limitation, shares sold under the Plan may be newly-issued
      shares or outstanding shares that have been reacquired by the Company in a
      private transaction or open market purchases or both. If any option
      granted under the Plan shall for any reason terminate without having been
      exercised, the shares not purchased under such option shall again become
      available for the Plan.

                                      -4-
<PAGE>

4.2   In the event of any reorganization, recapitalization, stock split, reverse
      stock split, stock dividend, combination of shares, merger, consolidation,
      acquisition of property or shares, separation, asset spin-off, stock
      rights offering, liquidation or other similar change in the capital
      structure of the Company after the date on which the Board adopts this
      Plan, the Committee shall make such adjustment, if any, as it deems
      appropriate in the number, kind and purchase price of the shares available
      for purchase under the Plan. In the event that, after a Grant Date, there
      occurs a dissolution or liquidation of the Company, except pursuant to a
      transaction to which Section 424(a) of the Code applies, each option to
      purchase Common Stock shall terminate, but the Participant holding such
      option shall have the right to exercise his or her option prior to such
      dissolution or liquidation.

                          V. Eligibility Requirements
                             ------------------------

5.1   Except as provided in Section 5.2, each Employee of the Company or a
      Participating subsidiary shall become eligible to participate in the Plan
      in accordance with Article VI on the first Enrollment Date following the
      Employee's completion of six months of employment by the Company or a
      Participating Subsidiary, as applicable, provided that the individual is
      an Employee on that Enrollment Date. Participation in the Plan is
      voluntary.

5.2   The following Employees are not eligible to participate in the Plan:

      (a)  Employees who, immediately upon enrollment in the Plan, would own
           directly or indirectly, or hold options or rights to acquire, an
           aggregate of 5% or more of the total combined voting power or value
           of all outstanding shares of all classes of stock of the Company or
           any Subsidiary (and for purposes of this paragraph, the rules of Code
           Section 424(d) shall apply, and stock that the Employee may purchase
           under outstanding options shall be treated as stock owned by the
           Employee);

      (b)  Employees who are customarily employed by the Company or a
           Participating Subsidiary for not more than five months in any
           calendar year;

      (c)  Employees who are customarily employed by the Company or a
           Participating Subsidiary for 20 hours or less per week;

      (d)  Employees who are prohibited by the laws of the nation of their
           residence or employment from participating in the Plan; and

      (e)  Employees who are members of a collective bargaining unit covered by
           a collective bargaining agreement; provided that participation in the
           Plan has been specifically considered (after review of the terms of
           the Plan) and rejected by the collective bargaining representative
           representing such employees.

5.3   Employees who are also directors or officers (as defined in Rule 16a-1(f)
      under the Exchange Act, as such rule may be amended from time to time) of
      the Company may participate only in accordance with the requirements of
      Rule 16b-3. The Plan is intended to conform to the extent necessary with
      all provisions of the Securities Act and the

                                      -5-
<PAGE>

      Exchange Act and all regulations and rules promulgated by the SEC
      thereunder, including Rule 16b-3. Notwithstanding anything herein to the
      contrary, the Plan shall be administered, and the options shall be granted
      and may be exercised, only in such a manner as to conform to such laws,
      rules and regulations. To the extent permitted by applicable law, the Plan
      and the options granted hereunder shall be deemed amended to the extent
      necessary to conform to such laws, rules and regulations.

                                VI. Enrollment
                                    ----------

6.1   Any Eligible Employee may enroll in the Plan as of an Enrollment Date.  In
      order to enroll with respect to any Enrollment Period, an Eligible
      Employee must complete, sign and submit to the Company an enrollment form
      in such form as provided by the Committee which shall include, among other
      items, the Eligible Employee's contribution election. Any enrollment form
      received by the Company before the Cut-Off Date will be effective as of
      the Enrollment Date to which it relates and shall continue in effect until
      (i) the end of the last payroll period in the Enrollment Period and
      succeeding Enrollment Periods unless the Employee has specified that the
      enrollment form shall not continue in effect beyond a designated
      enrollment period, (ii) the day before the start of a succeeding
      enrollment period for which the Employee has submitted a new enrollment
      form prior to the applicable Cut-Off Date, or (ii) the date during the
      Enrollment Period that the Employee withdraws from the Plan or has a
      termination of employment in accordance with Article X.

                      VII. Grant of Options on Enrollment
                           ------------------------------

7.1   Enrollment by an Eligible Employee in the Plan as of an Enrollment Date
      will constitute the grant by the Company to such Participant on the
      Enrollment Date of an option to purchase shares of Common Stock from the
      Company pursuant to the Plan.

7.2   An option granted to a Participant under the Plan shall give the
      Participant a right to purchase on a Purchase Date any number of whole
      shares of Common Stock which is not less than ten (10) and not more than
      the lesser of the following amounts, whichever is applicable:

      (a)  the product of (i) the percentage of Base Earnings designated in the
           Participant's enrollment form in accordance with Section 8.1 and (ii)
           the Participant's semiannualized Base Earnings at the rate in effect
           on the applicable Enrollment Date, divided by 85% of the Fair Market
           Value of a share of Common Stock as of the Grant Date for the option.
           For this purpose, the Base Earnings of an hourly-paid Employee shall
           be the sum of such Employee's hourly rate of base pay as of the
           beginning of the Enrollment Period multiplied by the number of
           regularly scheduled hours, plus the Employee's overtime rate of pay
           as of the beginning of the Enrollment Period multiplied by the number
           of scheduled overtime hours, that the Employee is expected to work
           during the Enrollment Period.

                                      -6-
<PAGE>

      (b)  the dollar amount designated in the Participant's enrollment form in
           accordance with Section 8.1, divided by 85% of the Fair Market Value
           of a share of Common Stock as of the Grant Date for the option.

7.3   Each option granted under the Plan shall have the following terms:

      (a)  whether or not all shares subject thereto have been purchased, the
           option will expire on the earliest to occur of (i) the completion of
           the purchase of shares on the Purchase Date with respect to which
           such option was granted; or (ii) the date on which participation of
           such Participant in the Plan terminates for any reason;

      (b)  payment for shares purchased under the option will be made only in
           accordance with Article VIII;

      (c)  purchase of shares upon exercise of the option will be accomplished
           only in accordance with Article IX;

      (d)  the purchase price per share under the option will be determined as
           provided in Article IX;

      (e)  notwithstanding Section 8.1, no Participant shall be granted an
           option which permits the Participant's rights to purchase shares
           under all employee stock purchase plans under Section 423 of the Code
           of the Company and any Subsidiary to accrue at a rate which exceeds
           $25,000 of Fair Market Value of such shares (determined at the time
           such option is granted) for each calendar year in which such option
           is outstanding at any time as determined in accordance with Section
           423(b)(8) of the Code and the treasury regulations thereunder;

      (f)  the option will in all respects be administered so as to comply with
           Section 423 of the Code; and

      (g)  the option will in all respects be subject to the terms and
           conditions of the Plan, as amended from time to time and as
           interpreted by the Committee from time to time.

                              VIII. Contributions
                                    -------------

8.1   Each Participant may elect to make contributions at a rate equal to a
      specified dollar amount or to any whole percentage of his or her Base
      Earnings for each Enrollment Period, or such other lower maximum
      percentage of Base Earnings as the Committee may establish from time to
      time before the beginning of an Enrollment Period for all options to be
      granted during such Enrollment Period. The maximum an Employee may elect
      and authorize to have deducted for an Enrollment Period is the lesser of
      (i) 10% of his Base Earnings for such Enrollment Period, or (ii) $15,000
      (or such higher or lower amount established by the Committee from time to
      time). The dollar amount or rate of contribution shall be designated by
      the Participant in the enrollment form. Contributions shall be made only
      through an Employee's authorizing payroll withholding on the enrollment
      form.

                                      -7-
<PAGE>

8.2   Contributions shall be credited to a recordkeeping account for each
      Participant as soon as administratively feasible after withholding of Base
      Earnings. The Company shall be entitled to use of the contributions and
      shall have no obligation to set aside or pay interest on the contributions
      to any Participant.

8.3   During an Enrollment Period, no Participant may elect to increase, reduce
      or cease future contributions to the Plan for that Enrollment Period, but
      any Participant may withdraw from the Plan for the remainder of such
      Enrollment Period pursuant to Article X. A Participant may elect to
      increase or decrease the rate of contribution for any future Enrollment
      Period by delivery to the Company not later than the related Cut-Off Date
      of a new enrollment form indicating the revised rate of contribution.

8.4   Neither the Company nor any Participating Subsidiary shall make
      contributions to the Plan. No interest shall be credited to a
      Participant's account.

                            IX. Purchase of Shares
                                ------------------

9.1   Any option held by a Participant that was granted under this Plan and that
      remains outstanding as of a Purchase Date shall be deemed to have been
      exercised on such Purchase Date for the purchase of the number of whole
      shares of Common Stock which the funds accumulated in his or her account
      as of the Purchase Date will purchase at the applicable purchase price,
      but not in excess of the number of shares for which options have been
      granted to the Participant pursuant to Section 7.2. The applicable
      purchase price for any shares purchased under any option shall, unless the
      Committee in its discretion establishes a higher price, be 85% of the
      lower of:

      (a)  the Fair Market Value of a share of Common Stock on the Grant Date
           for such option; or

      (b)  the Fair Market Value of a share of Common Stock on the Purchase
           Date.

9.2   Within a reasonable time after the Purchase Date, the Company shall cause
      to be delivered to the Participant a certificate or certificates for the
      number of shares purchased by the Participant unless the Company has made
      arrangements to have the shares held at a bank or other appropriate
      institution in non-certificated form. If any law or applicable rule or
      regulation of the SEC or other body having jurisdiction shall require that
      the Company or the Participant to take any action in connection with the
      shares being purchased under the option, delivery of the certificate or
      certificates for such shares shall be postponed until the necessary action
      shall have been completed, which action shall be taken by the Company at
      its own expense, without unreasonable delay.

9.3   Any amount less than the price of a whole share of Common Stock which
      remains credited to a Participant's account on a Purchase Date shall be
      carried forward in such account for application on the next Purchase Date.

9.4   In the case of Participants employed by a Participating Subsidiary, the
      Committee may provide for Common Stock to be sold through the Subsidiary
      to such Participants, to the extent consistent with Section 423 of the
      Code.

                                      -8-
<PAGE>

9.5   If the aggregate number of shares of Common Stock for which an option is
      exercised on any Purchase Date in accordance with this Article IX, when
      aggregated with all shares of Common Stock previously granted under this
      Plan, would exceed the maximum number of shares reserved in Section 4.1,
      the Company shall make a pro rata allocation of the shares available for
      delivery and distribution in as nearly a uniform manner as shall be
      practicable and as it shall determine to be equitable, and the balance of
      payroll deductions credited to the account of each Participant under the
      Plan shall be returned to him or her without interest as promptly as
      possible.

9.6   If the payroll deductions credited to the account of the Participant
      exceeds the cost of the maximum number of shares that can be purchased by
      the Participant, the excess shall be returned to him or her without
      interest as promptly as possible. The number of shares which a Participant
      is permitted to purchase shall be further limited by the amount of payroll
      deductions withheld as of the Purchase Date.

9.7   If a Participant or former Participant sells, transfers, or otherwise
      disposes of Common Stock purchased pursuant to an option granted under the
      Plan within two years after the date such option is granted or within one
      year after the Purchase Date to which such option relates, such
      Participant or former Participant shall notify the Company in writing of
      such sale, transfer or other disposition within 10 days of the
      consummation of such sale, transfer or other disposition, and shall remit
      to the Company or authorize the Company to withhold from other sources
      such amount as the Company may determine to be necessary to satisfy any
      federal, state or local tax withholding obligations of the Company or
      Participating Subsidiary. The Committee may from time to time establish
      rules and procedures (including postponing delivery of shares until the
      expiration of the two-year or one-year period) to cause the withholding
      requirements to be satisfied.

                  X. Withdrawal From the Plan; Termination of
                     ----------------------------------------
                        Employment and Leave of Absence
                        -------------------------------

10.1  Withdrawal from the Plan.  A Participant may withdraw from the Plan in
      full (but not in part) with respect to any Enrollment Period at any time
      up to four weeks prior to a Purchase Date upon delivery to the Company of
      a notice of withdrawal, or such shorter time in advance of a Purchase Date
      as the Committee may permit. If notice is timely received, all funds
      credited to a Participant's account shall not be used to purchase Common
      Stock, but shall instead be distributed to him or her without interest as
      soon as administratively feasible. An Employee who has withdrawn during an
      Enrollment Period may not return funds to the Company during the same
      Enrollment Period and require the Company to apply those funds to the
      purchase of Common Stock. Any Eligible Employee who has withdrawn from the
      Plan may, however, re-enroll in the Plan on the next subsequent Enrollment
      Date following withdrawal in accordance with the provisions of Article VI.

10.2  Termination of Employment.  Participation in the Plan terminates
      immediately when a Participant ceases to be employed by the Company or
      Participating Subsidiary for any reason whatsoever (including death or
      disability, or upon his or her employer ceasing to be a Participating
      Subsidiary for any reason including its ceasing to be a Subsidiary) or

                                      -9-
<PAGE>

      otherwise ceases to be an Eligible Employee. As soon as administratively
      feasible after termination of participation, the Company shall pay to the
      Participant or his or her beneficiary or legal representative all amounts
      credited to the Participant's account, without interest.

10.3  Leave of Absence.  Unless a Participant has voluntarily withdrawn from the
      Plan, Common Stock will be purchased for the account of a Participant who
      is on leave of absence on the Purchase Date next following the start of
      that Participant's leave of absence. Participation of such Participant in
      the Plan will terminate immediately after the purchase of shares on such
      Purchase Date, unless:

      (a)  the leave of absence is due to illness, injury or other reason
           approved by the Committee; or

      (b)  the Participant's right to return to active employment after such
           leave is guaranteed by contract or statute.

                        XI. Designation of Beneficiary
                            --------------------------

11.1  Each Participant may designate in writing one or more beneficiaries to
      receive the amount in his or her account in the event of death and may, in
      his or her sole discretion, change such designation in writing at any time
      without the consent of any designated beneficiary. Any such designation
      shall be effective upon receipt by the Company and shall control over any
      disposition by will or otherwise.

11.2  As soon as administratively feasible after the death of a Participant,
      amounts credited to his or her account shall be paid (without interest) in
      cash to the designated beneficiaries or, in the absence of a designation,
      to the executor, administrator or other legal representative of the
      Participant's estate. Such payment shall relieve the Company of further
      liability with respect to the Plan on account of the deceased Participant.
      If more than one beneficiary is designated, each beneficiary shall receive
      an equal portion of the account unless the Participant has given express
      contrary instructions.

11.3  No beneficiary shall, prior to the death of the Participant by whom he or
      she has been designated, acquire any interest in the amounts credited to
      the Participant's account under the Plan.

                              XII. Miscellaneous
                                   -------------

12.1  Restrictions on Transfer.  Options granted hereunder may not be
      transferred otherwise than by will or the laws of descent and
      distribution. An option may not be exercised during a Participant's
      lifetime other than by the Participant. A Participant may direct the
      Company in the enrollment form that share certificates issued by the
      Company be issued to the Participant in the Participant's name, or if the
      Participant so indicates in the enrollment form, in the Participant's name
      together with the name of one or more other persons, in joint tenancy with
      right of survivorship or spousal community property, or in certain forms
      of trusts approved by the Committee. The rights of a Participant under the
      Plan shall not be assignable by such Participant by operation of law or
      otherwise.

                                      -10-
<PAGE>

12.2  Administrative Assistance.  If the Committee in its discretion so elects,
      it may retain a brokerage firm, bank or other financial institution to
      assist in the purchase of shares, delivery of reports or other
      administrative aspects of the Plan. If the Committee so elects, each
      Participant shall (unless prohibited by applicable law) be deemed upon
      enrollment in the Plan to have authorized the establishment of an account
      on his or her behalf at such institution. Shares purchased by a
      Participant under the Plan shall be held in the account in the
      Participant's name, or if the Participant so indicates in the enrollment
      form, in the Participant's name together with the name of one or more
      other persons, in joint tenancy with right of survivorship or spousal
      community property, or in certain forms of trusts approved by the
      Committee.

12.3  Costs.  All costs and expenses incurred in administering the Plan shall be
      paid by the Company, except that any stamp duties, transfer taxes and any
      brokerage fees applicable to participation in the Plan shall be charged to
      the account of such Participant by the Company.

12.4  Equal Rights and Privileges.  All Eligible Employees shall have equal
      rights and privileges with respect to the Plan so that the Plan qualifies
      as an "employee stock purchase plan" within the meaning of Section 423 or
      any successor provision of the Code and the related regulations.
      Notwithstanding any term of the Plan, any provision of the Plan which is
      inconsistent with Section 423 or any successor provision shall
      automatically be reformed to comply with the requirements of Section 423.

12.5  Applicable Law.  The Plan shall be governed by the substantive laws
      (excluding the conflict of laws rules) of the State of Delaware.

12.6  Amendment and Termination.  The Board may amend, alter or terminate the
      Plan at any time. No amendment shall be effective unless within one year
      after it is adopted by the Board it is approved by the holders of a
      majority of the voting power of the Company's outstanding shares, if such
      amendment would require stockholder approval under Section 423 of the Code
      or the requirements of any securities exchange or quotation system on
      which the Common Stock is listed.

           If the Plan is terminated, the Board may elect to terminate all
      outstanding options either prior to their expiration or upon completion of
      the purchase of shares on the next Purchase Date, or may elect to permit
      options to expire in accordance with their terms (and participation to
      continue through such expiration dates). If the options are terminated
      prior to expiration, all funds contributed to the Plan that have not been
      used to purchase shares shall be returned to the Participants without
      interest as soon as administratively feasible.

12.7  No Right of Employment. Neither the grant nor the exercise of any rights
      to purchase shares under this Plan nor anything in this Plan shall impose
      upon the Company or any Participating Subsidiary any obligation to employ
      or continue to employ any employee. The right of the Company and the
      Participating Subsidiaries to terminate any employee shall not be
      diminished or affected because any rights to purchase shares have been
      granted to such employee.

                                      -11-
<PAGE>

12.8  No Right as Stockholder.  A Participant shall not by reason of any option
      have any right as a stockholder of the Company with respect to shares of
      Common Stock which may be purchased under the Plan until such shares have
      been delivered to him or her.

12.9  Requirements of Law.  The Company shall not be required to sell, issue, or
      deliver any shares of Common Stock under this Plan if such sale, issuance,
      or delivery might constitute a violation by the Company or the Participant
      of any provision of applicable law. Unless a registration statement or
      qualification under the Securities Act or any applicable state securities
      law is in effect with respect to the shares of Common Stock proposed to be
      delivered under the Plan, the Company shall not be required to deliver
      such shares if, in the opinion of the Company's counsel, such issuance
      could reasonably be expected to violate the Securities Act or such state
      securities law, as applicable.

           To the extent that such shares of Common Stock have not been
      registered or qualified under the Securities Act or any applicable state
      securities laws, the Company may impose restrictions upon the
      hypothecation or further sale or transfer of such shares (including the
      placement of appropriate legends on stock certificates) if, in the
      judgment of the Company's counsel, such restrictions are necessary or
      desirable to achieve compliance with the Securities Act or the securities
      laws of any state. If, in the opinion of the Company's counsel, any legend
      placed on a stock certificate for shares of Common Stock issued under the
      Plan is no longer required by applicable securities or other laws, the
      holder of such certificate shall be entitled to exchange such certificate
      for an unlegended certificate for a like number of shares.

           The Company shall use all reasonable efforts to register or qualify
      the Common Stock to be sold pursuant to the Plan under the Securities Act
      and any applicable state securities laws. The Company shall not be
      obligated to take any other action to cause the grant or exercise of any
      right or the issuance, sale, or deliver of shares pursuant to the exercise
      of any right to comply with any law.

      Executed this __________ day of __________, 2000.

                              OPEN PORT TECHNOLOGY, INC.

                                         By: __________________________
                                         Title: _______________________

                                                                    May 18, 2000

                                      -12-<PAGE>

                                                                   EXHIBIT 10.10

                          OPEN PORT TECHNOLOGY, INC.

                          SECOND AMENDED AND RESTATED
                         REGISTRATION RIGHTS AGREEMENT

                               January 27, 2000
<PAGE>

                          SECOND AMENDED AND RESTATED
                         REGISTRATION RIGHTS AGREEMENT

     This Second Amended and Restated Registration Rights Agreement (this
"Agreement") is entered into as of the 27/th/ day of January, 2000, among Open
Port Technology, Inc., an Illinois corporation (the "Company") and the persons
and entities set forth on Schedule 1 hereto, which includes the investor (the
                          ----------
"Series A Investor") party to the Series A Investment Agreement defined below
and designated as such on Schedule 1, the investors (the "Series B Investors")
                          ----------
party to the Series B Investment Agreement defined below and designated as such
on Schedule 1, the investors (the "Series C Investors") party to the Series C
   ----------
Investment Agreement defined below and designated as such on Schedule 1, the
                                                             ----------
investors (the "Series D Investors") party to the Series D Investment Agreement
defined below and designated as such on Schedule 1, and certain new investors
                                        ----------
(the "Series E Investors" and, together with the Series A Investor, the Series B
Investors, the Series C Investors and the Series D Investors, collectively, the
"Investors").

                                   RECITALS

     A.   Pursuant to the terms of an investment agreement (the "Series A
Investment Agreement"), dated as of July 27, 1995, as amended as of March 12,
1996, between the Company and the Series A Investor, the Company sold shares of
Series A Convertible Participating Preferred Stock of the Company, par value
$.001 per share (the "Series A Preferred Stock"), to the Series A Investor.

     B.   Pursuant to the terms of an investment agreement (the "Series B
Investment Agreement"), dated as of March 12, 1996, as amended as of April 19,
1996, February 6, 1997, March 19, 1997, between the Company and the Series B
Investors, the Company sold shares of Series B Convertible Participating
Preferred Stock of the Company, par value $.001 per share (the "Series B
Preferred Stock"), to the Series B Investors.

     C.   Pursuant to the terms of an investment agreement (the "Series C
Investment Agreement"), dated as of June 15, 1998, as amended as of February 4,
1999, among the Company, the Series C Investors, the Series A Investor and the
Series B Investors, the Company sold shares of Series C Convertible
Participating Preferred Stock of the Company, par value $.001 per share (the
"Series C Preferred Stock"), to the Series C Investors.

     D.   Pursuant to the terms of an investment agreement (the "Series D
Investment Agreement"), dated as of April 29, 1999, among the Company, the
Series D Investors, the Series C Investors, the Series B Investors, and the
Series A Investor, the Company sold shares of Series D Convertible Preferred
Stock of the Company, par value, $.001 per share (the "Series D Preferred
Stock"), to the Series D Investors.

     E.   The Company, the Series A Investor, the Series B Investors, the Series
C Investors and the Series D Investors are parties to that certain Amended and
Restated Registration Rights Agreement, dated as of June 15, 1998, as amended
(the "Existing Registration Rights Agreement").

                                       1
<PAGE>

     F.   The Series E Investors have agreed to purchase shares of Series E
Preferred Stock (as hereinafter defined) of the Company, pursuant to that
certain Series E Investment Agreement dated as of even date herewith (the
"Series E Investment Agreement") provided that the Company and the Investors
enter into this Agreement to amend and restate the Existing Amended and Restated
Registration Rights Agreement.

     G.   The Company and the Investors deem it desirable to (i) enter into this
Agreement in order to induce the Series E Investors to purchase the shares of
Series E Preferred Stock pursuant to the Series E Investment Agreement and (ii)
to amend and restate (and supersede and replace) the Existing Amended and
Restated Registration Rights Agreement.

     H.   The Company, in connection with certain financing arrangements has
issued warrants to acquire shares of Series C Preferred Stock to Third Coast
Venture Lease Partners I, L.P. ("Third Coast"), CID Mezzanine Capital, L.P.
("CIDMC") and Silicon Valley Bank (such warrants being collectively referred to
as the "Existing Warrants") and the Company may in the future enter into
additional financing arrangements pursuant to which the Company will issue
"Additional Warrants" (as that term is defined in Section 3.4 of the Series E
Investment Agreement); upon exercise of such Existing Warrants or such
Additional Warrants by the holder or holders thereof, such holder or holders
shall be deemed an "Investor" for all purposes hereof and Schedule 1 shall be
                                                          --------
amended to include such holder or holders designated as such without any action
of the Company or the other Investors.

                             TERMS AND CONDITIONS

     In consideration of the mutual covenants and agreements contained in this
Agreement and the Series E Investment Agreement, and intending to be legally
bound, the parties hereto agree to, and agree to amend and restate (and
supersede and replace), as applicable, the Existing Registration Rights
Agreement as follows:

     Section 1.  Definitions.  As used in this Agreement, the following terms
                 -----------
have the meanings indicated below or in the referenced sections of this
Agreement:

     "Common Stock:"  The Company's Common Stock, par value $.001 per share, as
      ------------
the same may be constituted from time to time.

     "Conversion Stock:"  The shares of the Common Stock that the Investors have
      ----------------
the right to acquire, or do acquire, pursuant to conversion of (a) the Series A
Preferred Stock of the Company acquired under the Series A Investment Agreement,
(b) the Series B Preferred Stock of the Company acquired under the Series B
Investment Agreement, (c) the Series C Preferred Stock of the Company acquired
under the Series C Investment Agreement, (d) the Series D Preferred Stock of the
Company acquired under the Series D Investment Agreement, (e) the Series E
Preferred Stock of the Company acquired under the Series E Investment Agreement,
(f) the Series C Preferred Stock of the Company issuable upon the exercise of
the Existing Warrants, (g) the Preferred Stock of the Company issuable upon the
exercise of any Additional

                                       2
<PAGE>

Warrants, (h) any other shares of Preferred Stock or other securities of the
Company issued or acquired pursuant to any future agreement between or among any
of the Investors and the Company or any current shareholder of the Company, (i)
any shares of Preferred Stock issued or payable to the Investors in connection
with any stock dividend, stock split, or recapitalization of the Company, and
(j) any shares of Preferred Stock issued to the Investors in replacement of or
upon partial exercise of any conversion rights applicable to any of the shares
of Preferred Stock described in the preceding clauses.

     "Demand Registration:"  See Section 3(a) and Section 3(b).
      -------------------        ------------     ------------

     "Exchange Act:"  The Securities Exchange Act of 1934, as amended from time
      ------------
to time.

     "Fully Diluted:"  Assuming conversion into Common Stock of all shares that
      -------------
are convertible into Common Stock and the exercise of all options and warrants
to purchase Common Stock.

     "Initial Public Offering:"  The first primary offering of Common Stock to
      -----------------------
the public by the Company registered pursuant to the Securities Act.

     "Majority of the Registrable Securities:"  51% or more of the Registrable
      --------------------------------------
Securities being registered unless the text of this Agreement indicates that it
is 51% or more of the Registrable Securities then issued and outstanding.

     "Non-Series E Registrable Securities:"  All Registrable Securities other
      -----------------------------------
than the Series E Registrable Securities.

     "Person:"  An individual, a partnership, a corporation, a limited liability
      ------
company, an association, a joint stock company, a trust, a joint venture, an
unincorporated organization, and a government entity or any department, agency,
or political subdivision thereof.

     "Piggyback Registration:"  See Section 4(a).
      ----------------------        ------------

     "Preferred Stock:"  The Series A Preferred Stock, the Series B Preferred
      ---------------
Stock, the Series C Preferred Stock, the Series D Preferred Stock and the Series
E Preferred Stock.

     "Public Offering:"  A primary offering of Common Stock by the Company
      ---------------
registered pursuant to the Securities Act.

     "Registrable Securities:"  The Conversion Stock.
      ----------------------

     "Registration Expenses:"  See Section 7.
      ---------------------        ---------

     "Restricted Securities:"  The Registrable Securities, subject to the
      ---------------------
provisions of Section 2(a).
              ------------

     "SEC:"  The United States Securities and Exchange Commission.
      ---

     "Securities Act:"  The Securities Act of 1933, as amended from time to
      --------------
time.

                                       3
<PAGE>

     "Series E Preferred Stock:"  The Company's Series E Convertible
      ------------------------
Participating Preferred Stock, par value $.001 per share, as the same may be
constituted from time to time.

     "Series E Registrable Securities:"  The Conversion Stock relating to the
      -------------------------------
Series E Preferred Stock.

     "Underwritten registration or underwritten offering:"  A registration in
      --------------------------------------------------
which securities of the Company are sold pursuant to a firm commitment
underwriting.

     Section 2.  Securities Subject to this Agreement.
                 ------------------------------------

          (a)  Registrable Securities.  The securities entitled to the
               ----------------------
     benefits of this Agreement are those Registrable Securities that are
     Restricted Securities. A Registrable Security ceases to be a Restricted
     Security when (i) it is registered under the Securities Act and disposed of
     in accordance with the registration statement covering it, or (ii) it is
     eligible to be sold or transferred in accordance with the requirements of
     Section (k) (or similar provisions then in effect) of Rule 144 promulgated
     by the SEC under the Securities Act ("Rule 144").

          (b)  Holders of Registrable Securities.  A Person is deemed to be a
               ---------------------------------
     holder of Registrable Securities whenever that Person owns, directly or
     beneficially, or has the right to acquire Registrable Securities,
     disregarding any legal restrictions upon the exercise of that right.

     Section 3.  Demand Registration.
                 -------------------

          (a)  Requests for Registration.
               -------------------------

               (i)  At any time after the earlier of: (i) a Public Offering or
          (ii) June 15, 2001, any stockholder or stockholders holding in the
          aggregate at least 7.6% of the Non-Series E Registrable Securities (a
          "Non-Series E Demand Registration") or at least 5% of the Series E
          Registrable Securities (a "Series E Demand Registration"), may at any
          time demand that the Company register all or part of his, her, or its
          Registrable Securities under the Securities Act (Non-Series E Demand
          Registrations and Series E Demand Registrations being collectively
          referred to as a "Demand Registration") on Forms S-1, S-2, or S-3 (or
          similar forms then in effect) promulgated by the SEC under the
          Securities Act. Within ten days after receipt of a demand, the Company
          will notify in writing all holders of Registrable Securities of the
          demand. Any holder who wants to include his, her, or its Registrable
          Securities in the Demand Registration must notify the Company within
          ten business days of receiving the notice of the Demand Registration.
          Except as provided in this Section 3, the Company will include in all
                                     ---------
          Demand Registrations all Registrable Securities for which the Company
          receives timely written demands for inclusion. All demands made
          pursuant to this Section 3(a) must specify the number of Registrable
                           ------------
          Securities to be registered and the intended method of disposing of
          the Registrable Securities.

                                       4
<PAGE>

               (ii) Notwithstanding anything to the contrary herein, the holders
          of the Series E Registrable Securities shall have a special right to
          require up to three demand registrations (the "Series E Special Demand
          Registration") after an Initial Public Offering, which may be
          exercised by holders of at least 5% of the Series E Registrable
          Securities the first of which may be exercised not earlier then 120
          days after the Company's Initial Public Offering; provided that this
          special right shall expire when the holders of Common Stock issued
          upon conversion of the Series E Preferred Stock are free to sell them
          under Rule 144(k) or hold less than 1% of the outstanding Common Stock
          of the Company. The Company shall use its best commercial efforts to
          cause the first such registration statement to become effective on the
          181st day after the effectiveness of the registration statement for
          the Company's Initial Public Offering, or if later, not later than 60
          days after the demand therefore is made. Each such registration
          statement shall be on Form S-1 or S-3, if available, and shall remain
          effective for 180 days, or if less, until the Common Stock registered
          thereunder is sold. The holders of such Common Stock may, but shall
          not be required to, sell the Common Stock in an underwritten offering
          under this special registration right. Within ten days after receipt
          of a demand, the Company will notify in writing all holders of Series
          E Registrable Securities of the demand. Any holder who wants to
          include his, her, or its Series E Registrable Securities in the Series
          E Special Demand Registration must notify the Company within ten
          business days of receiving the notice of the Series E Special Demand
          Registration. Except as provided in this Section 3, the Company will
                                                   ---------
          include in all Series E Special Demand Registrations all Series E
          Registrable Securities for which the Company receives timely written
          demands for inclusion. Notwithstanding the foregoing, no Series E
          Special Demand Registration shall be underwritten without the consent
          of the holders of a majority of the shares of the Series E Preferred
          Stock included in such registration.

          (b)  Form of Registration.  The Demand Registration will be on Form
               --------------------
     S-3 whenever the Company is permitted to use that form, unless the holders
     of a Majority of the Registrable Securities or the underwriter reasonably
     request registration on an expanded form. The Company will use its best
     commercial efforts to qualify for registration on Form S-3.

          (c)  Registration Expenses.  The Company will pay all Registration
               ---------------------
     Expenses for so many Demand Registrations as are demanded under Section
                                                                     -------
     3(a)(i), up to a maximum of four Demand Registrations and for so many
     -------
     Series E Special Demand Registrations as are demanded under Section
                                                                 -------
     3(a)(ii), up to a maximum of three Series E Special Demand Registrations;
     --------
     provided, however, that the total of Series E Demand Registrations and
     Series E Special Demand Registrations shall not exceed four; and provided,
     however, in the case of a Demand Registration, as applicable, not more than
     two Non-Series E Demand Registrations shall be on Form S-1, and provided
     further that, with respect to a Demand Registration on Form S-1, (i) the
     Demand Registration includes at least that number of shares of Conversion
     Stock equal to or greater than 5% of the shares of Common Stock then issued
     and outstanding, fully diluted, and (ii) holders of at least a majority of
     the Conversion Stock have approved the Demand Registration. A

                                       5
<PAGE>

     registration initiated as a Demand Registration will count for the purposes
     of the first sentence of this Section 3(c) if the registration is withdrawn
                                   ------------
     for any reason after such registration has been declared effective by the
     SEC.

          (d)  Selection of Underwriters. If a Demand Registration or a Series E
               -------------------------
     Special Demand Registration is to be underwritten, the holders of a
     Majority of the Registrable Securities requested to be included in the
     Demand Registration or a Series E Special Demand Registration and the
     Company shall mutually select the investment banker(s) and manager(s) that
     will administer the offering, and the Company shall enter into a customary
     underwriting agreement with those investment banker(s) and manager(s).

          (e)  Priority on Registrations.  If, in connection with a Demand
               -------------------------
     Registration, the managing underwriters give the Company and the holders of
     the Registrable Securities being registered a written opinion that the
     number of Registrable Securities requested to be included exceeds the
     number of securities that can be sold in the offering without having a
     material adverse effect on the price of such Registrable Securities, the
     Company will include in the registration only the number of Registrable
     Securities that the underwriters believe can be sold. The number of
     securities registered shall be allocated pro rata among the holders of
     Registrable Securities on the basis of the total number of Registrable
     Securities held by each holder requested to be included in the
     registration. If a Series E Special Demand Registration is underwritten,
     and the managing underwriters give the Company and the holders of the
     securities being registered a written opinion that the number of Series E
     Registrable Securities requested to be included in such Series E Special
     Demand Registration exceeds the number of securities that can be sold in
     the offering without having a material adverse effect on the price of such
     Series E Registrable Securities, the Company will include in the
     registration only the number of Series E Registrable Securities that the
     underwriters believe can be sold.

          (f)  Delay in Filing.
               ---------------

               (i)  The Company may delay the filing of the registration
          statement in connection with each Demand Registration for a period of
          not more than 120 days upon the advice of the investment banker(s) and
          manager(s) that will administer the offering that a delay is necessary
          or appropriate under the circumstances. The Company may not use this
          right to delay more than once with respect to any Demand Registration.

               (ii) With respect to Series E Special Demand Registrations made
          pursuant to Section 3(a)(ii) above, in the event that (i) the Company
          would, in accordance with advice of its outside counsel, be required
          to disclose in the prospectus contained in such registration
          statements information not otherwise then required by law to be
          publicly disclosed; and (ii) in the good faith judgment of the
          Company's Board of Directors, in accordance with advice of its outside
          counsel and financial advisors, there is reasonable likelihood that
          such disclosure, or any other action to be taken in connection with
          such prospectus, would materially and adversely affect or interfere
          with any financing, acquisition, merger

                                       6
<PAGE>

          or similar transaction involving the Company, the filing or continued
          effectiveness of the registration statements referred to above may be
          delayed by the Company during no more than three non-consecutive
          periods each aggregating not more than 30 days in any twelve-month
          period, provided that in one circumstance during a twelve-month period
                  --------
          two such 30-day periods may be consecutive; and provided that the
                                                          --------
          Company shall delay during any such blackout period the filing or
          effectiveness of any other registration statement required pursuant to
          the registration rights of the holders of any other securities of the
          Company.

          (g)  Limited Piggyback Right on Demand Registrations.
               -----------------------------------------------

               (i)   Whenever the holders of Registrable Securities demand a
          Demand Registration or a Series E Special Demand Registration, the
          Company may notify in writing the other holders of securities of the
          same type as the Registrable Securities or Series E Registrable
          Securities, as applicable, that are to be registered not later than
          the earlier to occur of (i) the 5th day following the Company's
          receipt of notice of exercise of the Demand Registration or a Series E
          Special Demand Registration right or (ii) 45 days prior to the
          anticipated filing date.

               (ii)  The Company may include in the Demand Registration or a
          Series E Special Demand Registration, as applicable, securities of the
          same type and class held by other holders, but only, in the case of
          either type of demand registration to be underwritten, to the extent
          that the managing underwriters give the Company their written opinion
          that the total number or dollar amount of securities requested to be
          included can be sold in the offering without having a material adverse
          effect on the price of such Registrable Securities or Series E
          Registrable Securities, as applicable. If the number or dollar amount
          of securities requested to be sold exceeds the amount that in the
          opinion of the managing underwriters can be sold in the offering
          without having a material adverse effect on the price of such
          Registrable Securities or Series E Registrable Securities, as
          applicable, the Company will include in the registration: (i) first,
          all Registrable Securities or Series E Registrable Securities, as
          applicable, and (ii) second, up to the full number or dollar amount of
          securities requested to be included in the registration in excess of
          the number or dollar amount of Registrable Securities or Series E
          Registrable Securities, as applicable to be registered (allocated pro
          rata among the holders of the securities in such proportions as the
          Company and those holders may agree).

               (iii) The holders of securities (including the Company) other
          than Registrable Securities to be registered pursuant to this Section
                                                                        -------
          3(g) shall enter into the same agreement with the managing
          ----
          underwriters as do the holders of the Registrable Securities.

               (iv)  If the Company registers any of its securities on its own
          behalf in a Demand Registration or Series E Special Demand
          Registration, as applicable (in

                                       7
<PAGE>

          accordance with the provisions of this Section 3(g)), that Demand
                                                 ------------
          Registration or Series E Special Demand Registration, as applicable
          shall not count for the purpose of determining the number of Demand
          Registrations or Series E Special Demand Registration, as applicable
          for which the Company is required under Section 3(c) to pay all
                                                  ------------
          Registration Expenses, and the Company shall pay all of the
          Registration Expenses of that registration.

               (v)   If any of the holders of any other securities of the
          Company register those securities in a Demand Registration or Series E
          Special Demand Registration in accordance with this Section 3(g),
                                                              ------------
          those holders shall pay the fees and expenses of their counsel and
          their pro rata share of the Registration Expenses not paid by the
          Company for any reason.

               (vi)  Holders of any other securities of the Company may register
          such securities in a Series E Special Demand Registration in
          accordance with this Section 3(g), provided that the holders of the
          Series E Registrable Securities are not required to participate in an
          underwritten public offering, and shall not be subject to any
          underwriter cutback with respect to such Series E Special Demand
          Registration unless the holders of the Series E Registrable Securities
          request that their shares be underwritten.

     Section 4.  Piggyback Registrations.
                 -----------------------

          (a)  Right to Piggyback.  Whenever the Company proposes to register
               ------------------
     any of its securities under the Securities Act (except for the registration
     of securities to be offered pursuant to an employee benefit plan on Form S-
     8, pursuant to a registration made on Form S-4, or any successor forms then
     in effect) at any time other than pursuant to a Demand Registration or a
     Series E Special Demand Registration and the registration form to be used
     may be used for the registration of the Registrable Securities (a
     "Piggyback Registration"), it will so notify in writing all holders of
     Registrable Securities and all executive officers of the Company who are
     also Founders (as defined in the Second Amended and Restated Voting and Co-
     Sale Agreement of even date herewith) not later than the earlier to occur
     of (i) the 5th day following the Company's receipt of notice of exercise of
     other demand registration rights, or (ii) 30 days prior to the anticipated
     filing date. The Common Stock owned by such Founders is hereafter referred
     to as "Founder Securities." Subject to the provisions of Section 4(c) and
                                                              ------------
     Section 4(d), the Company will include in the Piggyback Registration all
     ------------
     Registrable Securities and Founder Securities with respect to which the
     Company has received written requests for inclusion within 15 business days
     after the applicable holder's receipt of the Company's notice. The holders
     of Registrable Securities and Founder Securities may withdraw all or any
     part of the Registrable Securities or the Founder Securities from a
     Piggyback Registration at any time before three business days prior to the
     effective date of the Piggyback Registration. If a Piggyback Registration
     is an underwritten offering effected under Section 4(c), all Persons whose
                                                ------------
     securities are included in the Piggyback Registration must sell their
     securities on the same terms and conditions as apply to the

                                       8
<PAGE>

     securities being issued and sold by the Company. If a Piggyback
     Registration is an underwritten offering effected under Section 4(d), all
                                                             ------------
     Persons whose securities are included in the Piggyback Registration must
     sell their securities on the same terms and conditions as apply to the
     securities being sold by the Person(s) initiating the Piggyback
     Registration. A registration of Registrable Securities and Founder
     Securities pursuant to this Section 4 shall not be counted as a Demand
                                 ---------
     Registration under Section 3.
                        ---------

          (b)  Piggyback Expenses.  The Company shall pay to the holders of the
               ------------------
     Registrable Securities and the Founder Securities included in a Piggyback
     Registration all Registration Expenses of those holders.

          (c)  Priority on Primary Registrations. If a Piggyback Registration is
               ---------------------------------
     an underwritten primary registration on behalf of the Company and the
     managing underwriters give the Company their written opinion that the total
     number or dollar amount of securities requested to be included in the
     registration exceeds the number or dollar amount of securities that can be
     sold, the Company will include the securities in the registration in the
     following order of priority: first, all securities the Company proposes to
     sell; second, up to the full number or dollar amount of Registrable
     Securities requested to be included in the registration (allocated pro rata
     among the holders of Registrable Securities on the basis of the dollar
     amount or number of Registrable Securities requested to be included);
     third, up to the full number or dollar amount of Founder Securities
     requested to be included in the registration (allocated pro rata among the
     holders of Founder Securities on the basis of the dollar amount or number
     of Founder Securities requested to be included); and fourth, any other
     securities (provided they are of the same class as the securities sold by
     the Company) requested to be included allocated among the holders of the
     securities in such proportions as the Company and those holders may agree.

          (d)  Priority on Secondary Registrations.  If a Piggyback Registration
               -----------------------------------
     is an underwritten secondary registration on behalf of holders of the
     Company's securities, and the managing underwriters give the Company their
     written opinion that the dollar amount or number of securities requested to
     be included in the registration exceeds the dollar amount or number of
     securities that can be sold, the Company will include in the registration:
     (1) to the extent of 50% of the number or dollar amount of securities other
     than Registrable Securities that in the underwriter's opinion can be sold,
     the securities requested to be included in the registration, allocated
     among the holders of those securities in such proportions as the Company
     and those holders may agree, (2) to the extent of the balance, the
     Registrable Securities requested to be included, allocated pro rata among
     the holders of Registrable Securities on the basis of the dollar amount or
     number of securities requested to be included, and (3) to the extent of the
     balance, the Founder Securities requested to be included, allocated pro
     rata among the holders of Founder Securities on the basis of the dollar
     amount or number of securities requested to be included. If after including
     all of the Registrable Securities and Founder Securities the underwriters
     determine that there are additional securities that can be sold, then
     securities other than Registrable Securities and Founder Securities may be
     added to the registration.

                                       9
<PAGE>

          (e)  Selection of Underwriters.  If any Piggyback Registration is an
               -------------------------
     underwritten offering, the Company will select the investment banker(s) and
     manager(s) that will administer the offering, as long as the investment
     banker(s) and manager(s) are reasonably satisfactory to the holders of a
     Majority of the Registrable Securities (including, for purposes of this
     Section 4(e) only, the Founder Securities), and shall enter into a
     ------------
     customary underwriting agreement with the investment banker(s) and
     manager(s).

          (f)  Other Registrations.  The Company agrees that after filing a
               -------------------
     registration statement with respect to Registrable Securities and, if
     applicable Founder Securities, pursuant to Section 3 or this Section 4 that
                                                ---------         ---------
     has not been withdrawn or abandoned, the Company will not register any of
     its equity securities or securities convertible or exchangeable into or
     exercisable for its equity securities under the Securities Act, whether on
     its own behalf or at the request of any holder of those securities, until
     at least three months has elapsed from the effective date of the previous
     registration. This three-month hiatus does not apply to registrations of
     securities to be issued in connection with employee benefit plans, to
     permit exercise or conversions of previously issued options, warrants, or
     other convertible securities, or in connection with a Demand Registration.

     Section 5.  Holdback Agreements.
                 -------------------

          (a)  Restrictions on Public Sale by Securities Holders.  Each holder
               -------------------------------------------------
     of Registrable Securities whose securities are included in a registration
     statement agrees not to make any public sale or distribution of equity
     securities of the Company (except as part of the underwritten registration
     or pursuant to registration on Form S-8 or any successor form), including a
     sale pursuant to Rule 144, during the seven days prior to and the 180 days
     after the effective date of any underwritten Demand Registration or any
     underwritten Piggyback Registration unless the managing underwriters agree
     otherwise; provided, however, that the holders of Series E Registrable
     Securities shall only be subject to the foregoing holdback in respect of
     the Initial Public Offering; and provided further, however, that nothing in
     this Section 5(a) shall be deemed to in any way limit the rights of the
     holders of Series E Registrable Securities under Section 3(a)(ii) hereof.

          (b)  Restrictions on Public Sale by the Company and Others. The
               -----------------------------------------------------
     Company agrees not to make any public sale or distribution of its equity
     securities, or any securities convertible into or exchangeable or
     exercisable for its equity securities, including a sale under Regulation D
     of the SEC or under any exemption of the Securities Act (except as part of
     the underwritten registration or pursuant to registrations on Form S-8 or
     any successor form), during the seven days prior to and the 180 days after
     the effective date of any underwritten Demand Registration or any
     underwritten Piggyback Registration unless the managing underwriters agree
     otherwise. The Company also agrees to use its best commercial efforts to
     cause each holder of at least 5% (on a fully-diluted basis) of its equity
     securities or any securities convertible into or exchangeable or
     exercisable for its equity securities (other than Registrable Securities),
     purchased from the Company at any time on or after the date of this
     Agreement (other than in a registered public offering) to agree not to make
     any public sale or distribution of those securities, including a sale
     pursuant to Rule 144 (except as part of the underwritten registration, if
     permitted), during

                                       10
<PAGE>

the seven days prior to and the 180 days after the effective date of the
registration unless the managing underwriters agree otherwise.

Section 6.    Registration Procedures.
              -----------------------

     (a) Best Commercial Efforts. Whenever the holders of Registrable Securities
         -----------------------
request the registration of any Registrable Securities pursuant to this
Agreement, the Company shall use its best commercial efforts to register and to
permit the sale of the Registrable Securities in accordance with the intended
method of disposition. To carry out this obligation, the Company shall as
expeditiously as possible:

          (i)   prepare and file with the SEC, but in any event no later than 90
     days (or such shorter period as required by Section 3(c)(ii) of this
     Agreement) after receipt of a request to file a registration statement
     (subject to Section 3(f)), a registration statement on the appropriate form
                 ------------
     and use its best commercial efforts to cause the registration
     statement to become effective. At least three days before filing a
     registration statement or prospectus or at least one business day before
     filing any amendments or supplements thereto including Registrable
     Securities, the Company will furnish to the counsel of the holders of a
     Majority of the Registrable Securities being registered copies of all
     documents proposed to be filed for that counsel's review and approval,
     which approval shall not be unreasonably withheld or delayed;

          (ii)  notify immediately each seller of Registrable Securities of any
     stop order threatened or issued by the SEC and take all actions reasonably
     required to prevent the entry of a stop order or if entered to have it
     rescinded or otherwise removed;

          (iii) prepare and file with the SEC such amendments and supplements to
     the registration statement and the corresponding prospectus necessary to
     keep the registration statement effective for 90 days (or such longer
     period as required by Section 3(c)(ii) of this Agreement) or such shorter
     period as may be required to sell all Registrable Securities covered by the
     registration statement; and comply with the provisions of the Securities
     Act with respect to the disposition of all securities covered by the
     registration statement during each period in accordance with the sellers'
     intended methods of disposition as set forth in the registration statement;

          (iv)  furnish to each seller of Registrable Securities a sufficient
     number of copies of the registration statement, each amendment and
     supplement thereto (in each case including all exhibits), the corresponding
     prospectus (including each preliminary prospectus), and such other
     documents as a seller may reasonably request to facilitate the disposition
     of the seller's Registrable Securities;

          (v)   use its best commercial efforts to register or qualify the
     Registrable Securities under securities or blue sky laws of jurisdictions
     in the United States of

                                       11
<PAGE>

     America as any seller requests and will do any and all other acts and
     things that may be necessary or advisable to enable the seller to
     consummate the disposition of the seller's Registrable Securities;

          (vi)   use its best commercial efforts to cause the Registrable
     Securities covered by the registration statement to be registered with or
     approved by those governmental agencies or authorities necessary to enable
     each seller to consummate the disposition of its Registrable Securities;

          (vii)  notify each seller of Registrable Securities, at any time when
     a prospectus is required to be delivered under the Securities Act, of any
     event as a result of which the prospectus or any document incorporated
     therein by reference contains an untrue statement of a material fact or
     omits to state any material fact necessary to make the statements therein
     not misleading, and will prepare a supplement or amendment to the
     prospectus or any such document incorporated therein by reference so that
     thereafter the prospectus will not contain an untrue statement of a
     material fact or omit to state any material fact necessary to make the
     statements therein not misleading;

          (viii) cause all registered Registrable Securities covered by such
     registration to be listed on each securities exchange, if any, on which
     similar securities issued by the Company are then listed;

          (ix)   provide an institutional transfer agent and registrar and a
     CUSIP number for all Registrable Securities on or before the effective date
     of the registration statement;

          (x)    enter into such customary agreements (including an underwriting
     agreement in customary form) and take all other actions in connection with
     those agreements as the holders of the Registrable Securities b eing
     registered or the underwriters, if any, reasonably request to expedite or
     facilitate the disposition of the Registrable Securities;

          (xi)   make available for inspection by any seller of Registrable
     Securities, any underwriter participating in any disposition pursuant to
     the registration statement, and any attorney, accountant, or other agent of
     any seller of at least 5% of the securities being sold pursuant to the
     Registration Statement or underwriter, all financial and other records,
     pertinent corporate documents, and properties of the Company, and cause the
     Company's officers, directors, and employees to supply all information
     reasonably requested by any seller, underwriter, attorney, accountant, or
     agent in connection with the registration statement; provided that an
     appropriate confidentiality agreement is executed by any seller,
     underwriter, attorney, accountant or other agent;

          (xii)  in connection with any underwritten offering, obtain a "cold
     comfort" letter from the Company's independent public accountants in
     customary

                                       12
<PAGE>

     form and covering those matters customarily covered by "cold comfort"
     letters as the holders of the Registrable Securities being registered or
     the managing underwriters reasonably request (and the letter shall be
     addressed to holders of the Registrable Securities);

          (xiii) furnish, at the request of any holder of Registrable Securities
     being registered an opinion of the counsel representing the Company for the
     purposes of the registration, in the form and substance customarily given
     to underwriters in an underwritten public offering and satisfactory to the
     counsel representing the holders of Registrable Securities being
     registered, addressed to the underwriters, if any, and to the holders of
     Registrable Securities being registered; and

          (xiv)  use its best commercial efforts to comply with all applicable
     rules and regulations of the SEC, and make available to its security
     holders, as soon as practicable, an earnings statement complying with the
     provisions of Section 11(a) of the Securities Act and covering the
                   -------------
     period of at least twelve months, but not more than eighteen months,
     beginning with the first month after the effective date of the Registration
     Statement .

     (b) Distribution of Securities. From time to time, the Company may require
         --------------------------
each seller of Registrable Securities subject to the registration to furnish to
the Company information regarding the distribution of the securities subject to
the registration.

     (c) Prospectus. Each holder of Registrable Securities agrees by acquisition
         ----------
of those securities that, upon receipt of any notice from the Company of any
event of the kind described in Section 6(a)(vii), the holder will
                               -----------------
discontinue disposition of Registrable Securities until the holder receives
copies of the supplemented or amended prospectus contemplated by Section
                                                                 -------
6(a)(vii). In addition, if the Company requests, the holder will deliver
---------
to the Company (at the Company's expense) all copies, other than permanent file
copies then in the holder's possession, of the prospectus covering the
Registrable Securities current at the time of receipt of the notice. If the
Company gives any such notice, the time period mentioned in Section
                                                            -------
6(a)(iii) shall be extended by the number of days elapsing between the date
---------
of notice and the date that each seller receives the copies of the supplemented
or amended prospectus contemplated by Section 6(a)(iii).
                                      -----------------

     (d) Duty to Provide Information.  Whenever the holders of Registrable
         -------------------------
Securities have requested that any Registrable Securities be registered pursuant
to this Agreement, those holders shall notify the Company, at any time when a
prospectus relating thereto is required to be delivered under the Securities
Act, of the happening of any event, which as to any holder of Registrable
Securities is to his or its respective knowledge, as a result of which the
prospectus included in the registration statement contains an untrue statement
of a material fact or omits any fact necessary to make the statements therein
not misleading.

                                       13
<PAGE>

Section 7.    Registration Expenses.
              ---------------------

     (a) Defined. All Registration Expenses incident to the Company's
         -------
performance of or compliance with this Agreement shall be paid as provided in
this Agreement. The term "Registration Expenses" includes without limitation all
registration filing fees, professional fees, and other expenses of compliance
with federal, state, and other securities laws (including fees and disbursements
of counsel for the underwriters in connection with state or other securities law
qualifications and registrations); printing expenses, messenger, telephone, and
delivery expenses; fees and disbursements of counsel for the Company and for the
sellers of the Registrable Securities (subject to the provisions of Section
                                                                    -------
7(b)); fees and disbursements of all independent certified public accountants
----
(including the expenses of any audit or "cold comfort" letters required by or
incident to performance of the obligations contemplated by this Agreement); fees
and expenses of the underwriters (excluding discounts and commissions but
including liability insurance if the Company so desires or if the underwriters
so require); fees and expenses of any special experts retained by the Company at
the request of the managing underwriters in connection with the registration;
and fees and expenses of other Persons retained by the Company. The term
"Registration Expenses" does not include the Company's internal expenses
(including, without limitation, all salaries and expenses of its officers and
employees performing legal or accounting duties), the expense of any annual
audit, and the fees and expenses incurred in connection with the listing of the
securities to be registered on each securities exchange on which similar
securities issued by the Company are then listed, all of which shall be paid by
the Company under all circumstances.

     (b) Legal Fees and Expenses. In connection with each registration for which
         -----------------------
the Company is required to pay the Registration Expenses of the holders of
Registrable Securities, the Company will promptly reimburse those holders for
the reasonable fees and disbursements of one law firm, selected by the holders
of a Majority of the Registrable Securities, to serve as counsel to all the
holders.

     (c) Expenses Not Covered. To the extent the Company is not required to pay
         --------------------
Registration Expenses, each holder of securities included in any registration
will pay those Registration Expenses allocable to the holder's securities so
included, and any Registration Expenses not allocable will be borne by all
sellers in proportion to the number of securities each registers.

Section 8.    Indemnification.
              ---------------

     (a) Indemnification by Company. To the full extent permitted by law, the
         --------------------------
Company agrees to indemnify each holder of Registrable Securities, its officers
and directors, and each Person who controls the holder (within the meaning of
the Securities Act and the Exchange Act) against all losses, claims, damages,
liabilities, and expenses caused by any untrue or allegedly untrue statement of
material fact contained in any registration statement, prospectus, or
preliminary prospectus or any omission or alleged omission to state a material
fact required to be stated therein or necessary to make the

                                       14
<PAGE>

statements therein not misleading, except to the extent the untrue statement or
omission resulted from information that the holder furnished in writing to the
Company expressly for use therein or by the holder's failure to deliver a copy
of the registration statement or prospectus or any amendments or supplements
thereto to any purchaser after the Company has furnished the holder with the
relevant documents. In connection with a firm or best commercial efforts
underwritten offering, to the extent required by the managing underwriters, the
Company will indemnify the underwriters, their officers and directors, and each
Person who controls the underwriters (within the meaning of the Securities Act
and the Exchange Act), to the extent customary in such agreements.

     (b)  Indemnification by Holders of Securities.  In connection with any
          ----------------------------------------
registration statement, each participating holder of Registrable Securities will
furnish to the Company in writing the information and affidavits that the
Company reasonably requests for use in connection with any registration
statement or prospectus and each holder agrees to indemnify, to the extent
permitted by law, the Company, its directors and officers, and each Person who
controls the Company (within the meaning of the Securities Act and the Exchange
Act) against any losses, claims, damages, liabilities, and expenses resulting
from any untrue or allegedly untrue statement of a material fact or any omission
or alleged omission of a material fact required to be stated in the registration
statement or prospectus or any amendment thereof or supplement thereto necessary
to make the statements therein not misleading, but only to the extent that the
untrue statement or omission is contained in or omitted from any information or
affidavit the holder furnished in writing, or resulting from the holder's
failure to deliver a copy of the registration statement or prospectus or any
amendments or supplements thereto to any purchaser after the Company has
furnished the holder with the relevant documents; provided, however, that the
liability of each such participating holder of Registrable Securities shall be
limited to the proportion of any such loss, claim, damage, liability or expense
which is equal to the proportion that the public offering price of the shares
sold by such participating holder under such registration statement bears to the
total public offering price of all securities sold thereunder, but not in any
event to exceed the net proceeds received by such participating holder from the
sale of Registrable Securities covered by such registration statement.

     (c) Indemnification Proceedings. Any Person entitled to indemnification
         ---------------------------
under this Agreement will (i) give prompt notice to the indemnifying party of
any claim with respect to which it seeks indemnification, and (ii) unless in the
indemnified party's reasonable judgment a conflict of interest may exist between
the indemnified and indemnifying parties with respect to the claim, permit the
indemnifying party to assume the defense of the claim with counsel reasonably
satisfactory to the indemnified party. If the indemnifying party does not assume
the defense, the indemnifying party will not be liable for any settlement made
without its consent (but that consent may not be unreasonably withheld). No
indemnifying party will consent to entry of any judgment or will enter into any
settlement that does not include as an unconditional term the claimant's or
plaintiff's release of the indemnified party from all liability concerning the
claim or litigation. An indemnifying party who is not entitled to or elects not
to assume the defense of a claim will not be obligated to pay the fees and
expenses of more than one

                                       15
<PAGE>

     counsel for all parties indemnified by the indemnifying party with respect
     to the claim, unless in the reasonable judgment of any indemnified party a
     conflict of interest may exist between the indemnified party and any other
     indemnified party with respect to the claim, in which event the
     indemnifying party shall be obligated to pay the fees and expenses of
     additional counsel.

Section 9. Rule 144 and Rule 144A.
           ----------------------

        (a) Company Obligations. If the Company files a registration statement
            -------------------
     pursuant to the requirements of the Securities Act or Section 12 of the
     Exchange Act, the Company covenants that it will file the reports required
     to be filed by it under the Securities Act and the Exchange Act and the
     rules and regulations adopted by the SEC thereunder (or, if the Company is
     not required to file such reports, it will make publicly available other
     information), and it will take such further action to enable the holder to
     sell Registrable Securities without registration under the Securities Act
     within the limitation of the exemptions provided by (i) Rule 144 under the
     Securities Act as amended from time to time, or (ii) any similar rule or
     regulation hereafter adopted by the SEC. Upon the request of any holder of
     Registrable Securities, the Company will deliver to the holder a written
     statement as to whether it has complied with Rule 144 or any successor rule
     requirements. The Company also covenants that it will provide all such
     information and it will take such further action as any holder of
     Registrable Securities reasonably may request to enable the holder to sell
     Registrable Securities without registration under the Securities Act within
     the limitation of Rule 144A under the Securities Act, as amended from time
     to time, or any successor rule requirements.

        (b) Reliance on Rule 144. If any proposed sale of Registrable Securities
            --------------------
     may be effected by the holders thereof pursuant to Rule 144(k) without any
     adverse effect on the proposed sale, as determined by the holder in its
     sole discretion, including without limitation the contemplated sale price
     or the quantity of Registrable Securities to be sold, then the holders of
     the Registrable Securities covenant to rely upon Rule 144(k) in the sale
     thereof in lieu of requesting a Demand Registration; provided, however, the
     holders of Registrable Securities shall not be obligated to take any action
     so that they are eligible to use or rely upon Rule 144(k) in connection
     with any sale or distribution.

     Section 10.  Participation in Underwritten Registrations.  No Person may
                  -------------------------------------------
participate in any underwritten registration without (a) agreeing to sell
securities on the basis provided in underwriting arrangements approved by the
persons entitled hereunder to approve such arrangements (the holders of the
Registrable Securities in a Demand Registration pursuant to Section 3(d) and the
                                                            ------------
Company in a piggyback registration pursuant to Section 4(e)), and (b)
                                                ------------
completing and executing all questionnaires, powers of attorney, indemnities,
underwriting agreements, and other documents required by the underwriting
arrangements.

Section 11.    Miscellaneous.
               -------------
(a)  Adjustments Affecting Securities.  The Company will not take any action, or
     --------------------------------
     permit any change to occur, with respect to the Registrable Securities that
     would affect

                                       16
<PAGE>

     adversely the ability of the holders to include those
     securities in a registration undertaken pursuant to this Agreement or the
     marketability of the Registrable Securities in any registration; provided,
     however, that the Company shall be permitted to take such action or permit
     such change if (i) the Board of Directors of the Company determines that
     the action or change has a legitimate corporate purpose unrelated to the
     effect such action or change would have on the ability of the holders of
     Preferred Stock to include those securities in a registration undertaken
     pursuant to this Agreement or the marketability of the Registrable
     Securities in any registration and (ii) such action or change would not
     have a material adverse effect on the ability of such holders to include
     those securities in a registration undertaken pursuant to this Agreement or
     the marketability of the Registrable Securities in any registration.
     Nothing in this subsection 11(a) shall permit the Company to amend or
     modify Section 3(f)(ii) of this Agreement without the consent of the
     holders of a majority of the shares of Series E Preferred Stock.

          (b) Amendment. This Agreement may not be amended or modified, and no
              ---------
     provision hereof may be waived, without the written consent of the Company
     and the holders of at least a majority of the outstanding Registrable
     Securities; provided that with respect the amendment, modification or
     waiver of any provision herein relating solely to the special rights
     granted to the holders of the Series E Preferred Stock herein, such
     amendment, modification or waiver shall require the written consent of the
     Company and the holders of at least a majority of the Series E Preferred
     Stock or Series E Registrable Securities, as applicable.

          (c) Attorneys' Fees. In any legal action or proceeding brought to
              ---------------
     enforce any provision of this Agreement, the prevailing party shall be
     entitled to recover all reasonable expenses, charges, court costs, and
     attorneys' fees in addition to any other available remedy at law or in
     equity.

          (d) Benefit of Parties: Assignability. All of the terms and provisions
              ---------------------------------
     of this Agreement shall be binding upon and inure to the benefit of the
     parties and their respective successors and assigns, including without
     limitation all subsequent holders of securities entitled to the benefits of
     this Agreement who agree in writing to become bound by the terms of this
     Agreement; provided, however, the Company may not delegate its
     responsibilities or assign its rights under this Agreement without the
     prior written consent of the holders of a Majority of the Registrable
     Securities then issued and outstanding .

          (e) Cooperation. The parties agree that after execution of this
              -----------
     Agreement they will from time to time, upon the request of any other party
     and without further consideration, execute, acknowledge, and deliver in
     proper form any further instruments and take such other action as any other
     party may reasonably require to carry out effectively the intent of this
     Agreement.

          (f) Cumulative Remedies and Survival. The rights and remedies
              --------------------------------
     specified in this Agreement shall not be exclusive of any other right or
     remedy and shall be

                                       17
<PAGE>

     cumulative and in addition to every other right or remedy now or hereafter
     existing at law or in equity or by statute or otherwise that may be
     available to the Investors.

          (g) Counterparts. This Agreement may be executed simultaneously in
              ------------
     two or more counterparts each of which shall be deemed an original, but
     all of which together shall constitute one and the same instrument.

          (h) Entire Agreement. This Agreement, the Series A Investment
              ----------------
     Agreement the Series B Investment Agreement, the Series C Investment
     Agreement, the Series D Investment Agreement, the Series E Investment
     Agreement and the Second Amended and Restated Voting and Co-Sale Agreement
     (as defined in the Series E Investment Agreement) contains the entire
     understanding of the parties with respect to the subject matter hereof and
     thereof. There are no representations, promises, warranties, covenants, or
     undertakings other than those expressly set forth or provided for herein or
     therein.

          (i) Governing Law. Illinois law shall govern the interpretation,
              -------------
     construction, and enforcement of this Agreement and all transactions and
     agreements contemplated hereby, notwithstanding any state's choice of law
     rules to the contrary .

          (j) Interpretation. The terms and conditions of this Agreement
              --------------
     represent the results of bargaining and negotiations among the parties,
     each of which has been represented by counsel of its own selection, and
     none of which has acted under duress or compulsion, whether legal, economic
     or otherwise, and represent the results of a combined draftsmanship effort.
     Consequently, the terms and conditions hereof shall be interpreted and
     construed in accordance with their usual and customary meanings and the
     parties hereby expressly waive and disclaim in connection with the
     interpretation and construction hereof any rule of law or procedures
     requiring otherwise, specifically including but not limited to any rule of
     law to the effect that ambiguous or conflicting terms or conditions
     contained herein shall be interpreted or construed against the party whose
     counsel prepared this Agreement or any earlier draft hereof.

          (k) Listing. If the Common Stock is listed for trading on any national
              -------
     securities exchange, that listing shall include all shares of Conversion
     Stock (to the extent permitted by the rules of the exchange).

          (l) No Inconsistent Agreements. Except with the prior written consent
              --------------------------
     of the holders of a Majority of the Registrable Securities then issued and
     outstanding, the Company will not enter into any agreement with respect to
     its securities that shall grant to any Person registration rights that are
     senior to, are in conflict with, or will interfere with the practical
     realization of the rights provided under this Agreement.

          (m) Notices. All notices, requests, demands, or other communications
              -------
     that are required or may be given pursuant to the terms of this Agreement
     shall be in writing and delivery shall be deemed sufficient in all respects
     and to have been duly given on the date of service if delivered personally
     or by facsimile transmission if receipt is confirmed to the party to whom
     notice is to be given, or on the third day after mailing if mailed by

                                       18
<PAGE>

     first-class mail, return receipt requested, postage prepaid, and properly
     addressed to the addresses set forth in the Series E Investment Agreement
     or to such other addresses as the respective parties hereto shall from time
     to time designate to the others in writing.

          (n) Specific Performance. Each of the parties agrees that damages for
              --------------------
     a breach of or default under this Agreement would be inadequate and that in
     addition to all other remedies available at law or in equity the parties
     and their successors and assigns shall be entitled to specific performance
     or injunctive relief, or both, in the event of a breach or a threatened
     breach of this Agreement.

          (o) Table of Contents and Captions. The Table of Contents and captions
              ------------------------------
     of the sections and subsections of this Agreement are solely for convenient
     reference and shall not be deemed to affect the meaning or interpretation
     of any provision of this Agreement.

          (p) Validity of Provisions. Whenever possible, each provision of this
              ----------------------
     Agreement shall be interpreted in such a manner as to be effective and
     valid under applicable law. Should any part of this Agreement for any
     reason be declared by any court of competent jurisdiction to be invalid,
     that decision shall not affect the validity of the remaining portion, which
     shall continue in full force and effect as if this Agreement had been
     executed with the invalid portion eliminated, it being the intent of the
     parties that they would have executed the remaining portion of the
     Agreement without including any part or portion that may for any reason be
     declared invalid.

          (q) Waiver of Breach. Neither any waiver of any breach of, nor any
              ----------------
     failure to enforce any term or condition of, this Agreement shall operate
     as a waiver of any other breach of any term or condition, nor constitute
     nor be deemed a waiver or release of any other rights, in law or at equity,
     or claims that any party may have against any other party for anything
     arising out of, connected with, or based upon this Agreement. No waiver
     shall be enforceable against any party hereto unless set forth in a written
     instrument or agreement signed by that party. No waiver shall be deemed to
     occur as a result of the failure of any party to enforce any term or
     condition of this Agreement.

          (r) Additional Investor. The Company, in connection with certain
              -------------------
     financing arrangements has issued warrants to acquire shares of Series C
     Preferred Stock to Third Coast Venture Lease Partners I, L.P. ("Third
     Coast"), CID Mezzanine Capital, L.P. ("CIDMC") and Silicon Valley Bank
     (such warrants being collectively referred to as the "Existing Warrants")
     and the Company may in the future enter into additional financing
     arrangements pursuant to which the Company will issue "Additional Warrants"
     (as that term is defined in Section 3.4 of the Series E Investment
     Agreement); upon exercise of such Existing Warrants or such Additional
     Warrants by the holder or holders thereof, such holder or holders shall be
     deemed an "Investor" for all purposes hereof and Schedule 1 shall be
                                                      --------
     amended to include such holder or holders designated as such without any
     action of the Company or the other Investors.

                                       19
<PAGE>

                               [END OF AGREEMENT]

                    [REST OF PAGE INTENTIONALLY LEFT BLANK]

                                       20
<PAGE>

                                  Schedule 1
                                  ----------

         TO SECOND AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT

<TABLE>
<CAPTION>
                                                    Aggregate Number of Shares of
Holders of Series A Convertible                   Series A Convertible Participating
Participating Preferred Stock                              Preferred Stock
------------------------------------------------------------------------------------
<S>                                               <C>
CID Equity Capital III, L.P.                                  1,228,917
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
                                                    Aggregate Number of Shares of
Holders of Series B Convertible                   Series B Convertible Participating
Participating Preferred Stock                              Preferred Stock
------------------------------------------------------------------------------------
<S>                                               <C>
Frontenac VI Limited Partnership                              3,839,285

Joseph A. Piscopo                                               357,143

Royce J. Holland                                                 44,643

Ronald and Kathy Kory, JTWROS                                   151,787

Ronald Kory as Trustee of the Kory Associates                   116,070
 Pension Plan

David Aniol                                                      26,786

Robert Milburn                                                   44,643

Alvon Ramp                                                       26,786
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
                                                   Aggregate Number of Shares of
Holders of Series B Convertible                  Series B Convertible Participating
Participating Preferred Stock                             Preferred Stock
-----------------------------------------------------------------------------------
<S>                                              <C>
CID Equity Capital III, L.P.                                 1,607,142

CID Equity Capital V, L.P.                                     446,429

NEA Ventures 1997, L.P.                                          4,464

New Enterprise Associates VII, Limited                       3,049,107
 Partnership

MKW Partners, L.P.                                             475,793

Douglas Cogswell                                                21,628

Hollis Family Limited Partnership #1, f/k/a                    163,294
 Hollis Family Limited Partnership
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
                                                    Aggregate Number of Shares of
Holders of Series B Convertible                   Series B Convertible Participating
Participating Preferred Stock                              Preferred Stock
------------------------------------------------------------------------------------
<S>                                               <C>
Battery Ventures III, L.P.                                    2,857,143

Jonathan N. Zakin                                               223,214

NEA Presidents' Fund, L.P.                                       71,429
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
                                                   Aggregate Number of Shares of
Holders of Series C Convertible                  Series C Convertible Participating
Participating Preferred Stock                             Preferred Stock
-----------------------------------------------------------------------------------
<S>                                              <C>
Microsoft Corporation                                        2,469,136

Oak Investment Partners VII, Limited                           963,456
 Partnership

Oak VII Affiliates Fund, Limited Partnership                    24,198

Northwestern University                                         12,346
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
Holders of Series D Convertible                   Aggregate Number of Shares of Series
Preferred Stock                                      D Convertible Preferred Stock
--------------------------------------------------------------------------------------
<S>                                               <C>
New Enterprise Associates VII, Limited                           204,241
 Partnership

NEA Presidents' Fund, L.P.                                         3,118

Frontenac VI Limited Partnership                                 243,682

Battery Ventures III, L.P.                                       189,718

Donald R. Hollis                                                  62,363

Hollis Family Limited Partnership I (f/k/a                        93,546
 Hollis Family Limited Partnership)
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
                                                 Aggregate Number of Shares of
Holders of Series D Convertible                      Series D Convertible
Preferred Stock                                         Preferred Stock
------------------------------------------------------------------------------
<S>                                              <C>
Oak Investment Partners VII, Limited                             48,550
Partnership

Joseph A. Piscopo                                                44,277

Royce J. Holland                                                  2,945

Ronald Kory and Kathy Kory, JTWROS                               41,795

Oak VII Affiliates Fund, L.P.                                     1,219
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
                                                  Aggregate Number of Shares of Series
Holders of Series E Convertible                  E Convertible Participating Preferred
Participating Preferred Stock                                    Stock
---------------------------------------------------------------------------------------
<S>                                              <C>
Crestwood Capital Partners, L.P.                               161,491

Crestwood Capital Partners II, L.P.                            105,590

Bridgewood Capital Partners, L.P.                               26,708

Crestwood Capital International, Ltd.                           16,770

Chelsey Capital                                                310,559

Kobrick Fund, L.P.                                             323,000
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
                                                  Aggregate Number of Shares of Series
Holders of Series E Convertible                  E Convertible Participating Preferred
Participating Preferred Stock                                    Stock
---------------------------------------------------------------------------------------
<S>                                              <C>
Kobrick Investment Fund, LP                                    236,000

Kobrick Offshore Fund, Ltd.                                     62,118

Crown Growth Partners, L.P.                                    465,839

Parson Finance Limited                                         155,279

Roundtable Associates, LLP                                      62,112

Hare & Co. as nominee for John Hancock Global                  527,950
Technology Fund

</TABLE>
<PAGE>

<TABLE>
<CAPTION>
                                                  Aggregate Number of Shares of Series
Holders of Series E Convertible                  E Convertible Participating Preferred
Participating Preferred Stock                                    Stock
---------------------------------------------------------------------------------------
<S>                                              <C>
Bluestone AFA Fund                                             248,447

Open Tech LLC                                                  776,398

Winfield Capital Corp.                                         621,118

United States Development Capital Portfolio                    683,230
 Company

Battery Ventures III, L.P.                                     504,947

Brookside Capital Partners Fund, L.P.                        6,211,180
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
                                                  Aggregate Number of Shares of Series
Holders of Series E Convertible                  E Convertible Participating Preferred
Participating Preferred Stock                                    Stock
---------------------------------------------------------------------------------------
<S>                                              <C>
WPG Software Fund, L.P.                                        317,857

WPG Institutional Software Fund, L.P.                          722,981

WPG Raytheon Software Fund, L.P.                               511,957

WPG Institutional Networking Fund, L.P.                         48,157

WPG Networking Fund, L.P.                                      430,013

WPG Raytheon Networking Fund, L.P.                           1,065,308
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
                                                  Aggregate Number of Shares of Series
Holders of Series E Convertible                  E Convertible Participating Preferred
Participating Preferred Stock                                    Stock
---------------------------------------------------------------------------------------
<S>                                              <C>
Raj Mehra                                                        9,317

CID Equity Capital V L.P.                                      265,944

CID Mezannine                                                  180,850

Frontenac VI Limited Partnership                               408,817

MKW Partners, L.P.                                              48,447

Microsoft Corporation                                          179,841
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
                                                  Aggregate Number of Shares of Series
Holders of Series E Convertible                  E Convertible Participating Preferred
Participating Preferred Stock                                    Stock
---------------------------------------------------------------------------------------
<S>                                              <C>
New Enterprise Associates VII, Limited                         348,508
 Partnership

Oak Investment Partners VII, Limited                            81,450
 Partnership
                                                                 2,046
Oak VII Affiliates Fund Limited Partnership
                                                                74,281
Joseph A. Piscopo
                                                               264,409
Essex Private Placement Fund III - A, Limited
 Partnership

Essex Private Placement Fund III - B, Limited                  977,827
 Partnership
</TABLE>

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00010-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00010-of-00352.parquet"}]]