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                                                                    Exhibit 10.4

                                UNICA CORPORATION
                        2005 EMPLOYEE STOCK PURCHASE PLAN
                           (as amended as of July 2005
                              and October 25, 2005)

The purpose of this Plan is to provide eligible employees of Unica Corporation
(the "Company") and certain of its subsidiaries with opportunities to purchase
shares of the Company's common stock, $0.01 par value (the "Common Stock"),
commencing on February 1, 2006. A total of 1,000,000 shares of Common Stock in
the aggregate have been approved for this purpose. This Plan is intended to
qualify as an "employee stock purchase plan" as defined in Section 423 of the
Internal Revenue Code of 1986, as amended (the "Code"), and the regulations
promulgated thereunder, and shall be interpreted consistent therewith.

1. Administration. The Plan will be administered by the Company's Board of
Directors (the "Board") or by a Committee appointed by the Board (the
"Committee"). The Board or the Committee has authority to make rules and
regulations for the administration of the Plan and its interpretation and
decisions with regard thereto shall be final and conclusive.

2. Eligibility. All employees of the Company, including directors who are
employees, and all employees of any subsidiary of the Company (as defined in
Section 424(f) of the Code) designated by the Board or the Committee from time
to time (a "Designated Subsidiary"), are eligible to participate in any one or
more of the offerings of Options (as defined in Section 9) to purchase Common
Stock under the Plan provided that:

         (a) they are customarily employed by the Company or a Designated
Subsidiary for more than 20 hours a week and for more than five months in a
calendar year;

         (b) they have been employed by the Company or a Designated Subsidiary
for at least three months prior to enrolling in the Plan; and

         (c) they are employees of the Company or a Designated Subsidiary on the
first day of the applicable Plan Period (as defined below).

No employee may be granted an option hereunder if such employee, immediately
after the option is granted, owns 5% or more of the total combined voting power
or value of the stock of the Company or any subsidiary. For purposes of the
preceding sentence, the attribution rules of Section 424(d) of the Code shall
apply in determining the stock ownership of an employee, and all stock that the
employee has a contractual right to purchase shall be treated as stock owned by
the employee.

3. Offerings. The Company will make one or more offerings ("Offerings") to
employees to purchase stock under this Plan. Offerings will begin each February
15 and August 15, or the first business day thereafter (the "Offering
Commencement Dates"). Each Offering Commencement Date will begin a six month
period (a "Plan Period") during which payroll deductions will be made and held
for the purchase of Common Stock at the end of the Plan Period. The Board or the
Committee may, at its discretion, choose a different Plan Period of twelve
months or less for subsequent Offerings.

4. Participation. An employee eligible on the Offering Commencement Date of any
Offering may participate in such Offering by completing and forwarding a payroll
deduction authorization form to the employee's appropriate payroll office prior
to the applicable Offering Commencement Date within the time specified by the
Company. The form will authorize a regular payroll deduction from the
Compensation (as defined below) received by the employee during the Plan Period.
Unless an employee
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files a new form or withdraws from the Plan, his deductions and purchases will
continue at the same rate for future Offerings under the Plan as long as the
Plan remains in effect. The term "Compensation" means the amount of money paid
for base salary, sales commissions, and incentive and bonus awards.

5. Deductions. The Company will maintain payroll deduction accounts for all
participating employees. With respect to any Offering made under this Plan, an
employee may authorize a payroll deduction in any dollar amount up to the lesser
of (a) 10% of the Compensation the employee receives during the Plan Period or
such shorter period during which deductions from payroll are made and (b)
$12,500. Payroll deductions may be at a rate of between 1% and 10% (inclusive),
in whole percentages, of Compensation, with any change in compensation during
the Plan Period to result in an automatic corresponding change in the dollar
amount withheld.

6. Deduction Changes. An employee may decrease or discontinue his payroll
deduction once during any Plan Period, by filing a new payroll deduction
authorization form. However, an employee may not increase his payroll deduction
during a Plan Period. If an employee elects to discontinue his payroll
deductions during a Plan Period, but does not elect to withdraw his funds
pursuant to Section 8 hereof, funds deducted prior to his election to
discontinue will be applied to the purchase of Common Stock on the Exercise Date
(as defined below).

7. Interest. Interest will not be paid on any employee accounts, except to the
extent that the Board or the Committee, in its sole discretion, elects to credit
employee accounts with interest at such per annum rate as it may from time to
time determine.

8. Withdrawal of Funds. An employee may at any time prior to the close of
business on the last business day in a Plan Period and for any reason
permanently draw out the balance accumulated in the employee's account and
thereby withdraw from participation in an Offering. Partial withdrawals are not
permitted. The employee may not begin participation again during the remainder
of the Plan Period. The employee may participate in any subsequent Offering in
accordance with terms and conditions established by the Board or the Committee.

9. Purchase of Shares. On the Offering Commencement Date of each Plan Period,
the Company will grant to each eligible employee who is then a participant in
the Plan an option ("Option") to purchase on the last business day of such Plan
Period (the "Exercise Date"), at the Option Price hereinafter provided for, the
largest number of whole shares of Common Stock of the Company as does not exceed
the number of shares determined by multiplying $2,083 by the number of full
months in the Offering Period and dividing the result by the closing price (as
defined below) on the Offering Commencement Date of such Plan Period.

      Notwithstanding the above, no employee may be granted an Option that
permits his rights to purchase Common Stock under this Plan and any other
employee stock purchase plan (as defined in Section 423(b) of the Code) of the
Company and its subsidiaries, to accrue at a rate that exceeds $25,000 of the
fair market value of such Common Stock (determined at the Offering Commencement
Date of the Plan Period) for each calendar year in which the Option is
outstanding at any time.

      The purchase price for each share purchased will be 95% of the closing
price of the Common Stock on the Exercise Date (the "Option Exercise Price").
Such closing price shall be (a) the closing price on any national securities
exchange on which the Common Stock is listed, (b) the closing price of the
Common Stock on the Nasdaq National Market or (c) the average of the closing bid
and asked prices in the over-the-counter-market, whichever is applicable, as
published in The Wall Street Journal. If no sales of Common Stock were made on
such a day, the price of the Common Stock for purposes of clauses (a) and (b)
above shall be the reported price for the next preceding day on which sales were
made.
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      Each employee who continues to be a participant in the Plan on the
Exercise Date shall be deemed to have exercised his Option at the Option Price
on such date and shall be deemed to have purchased from the Company the number
of full shares of Common Stock reserved for the purpose of the Plan that his
accumulated payroll deductions on such date will pay for, but not in excess of
the maximum number determined in the manner set forth above.

      Any balance remaining in an employee's payroll deduction account at the
end of a Plan Period will be automatically refunded to the employee, except that
any balance that is less than the purchase price of one share of Common Stock
will be carried forward into the employee's payroll deduction account for the
following Offering, unless the employee elects not to participate in the
following Offering under the Plan, in which case the balance in the employee's
account shall be refunded.

10. Issuance of Certificates. Certificates representing shares of Common Stock
purchased under the Plan may be issued only in the name of the employee, in the
name of the employee and another person of legal age as joint tenants with
rights of survivorship, or (in the Company's sole discretion) in the name of a
brokerage firm, bank or other nominee holder designated by the employee. The
Company may, in its sole discretion and in compliance with applicable laws,
authorize the use of book entry registration of shares in lieu of issuing stock
certificates.

11. Rights on Retirement, Death or Termination of Employment. In the event of a
participating employee's termination of employment prior to the last business
day of a Plan Period, no payroll deduction shall be taken from any pay due and
owing to an employee and the balance in the employee's account shall be paid to
the employee or, in the event of the employee's death, (a) to a beneficiary
previously designated in a revocable notice signed by the employee (with any
spousal consent required under state law) or (b) in the absence of such a
designated beneficiary, to the executor or administrator of the employee's
estate or (c) if no such executor or administrator has been appointed to the
knowledge of the Company, to such other person(s) as the Company may, in its
discretion, designate. If, prior to the last business day of the Plan Period,
the Designated Subsidiary by which an employee is employed shall cease to be a
subsidiary of the Company, or if the employee is transferred to a subsidiary of
the Company that is not a Designated Subsidiary, the employee shall be deemed to
have terminated employment for the purposes of this Plan.

12. Optionees Not Stockholders. Neither the granting of an Option to an employee
nor the deductions from his pay shall constitute such employee a stockholder of
the shares of Common Stock covered by an Option under this Plan until such
shares have been purchased by and issued to him.

13. Rights Not Transferable. Rights under this Plan are not transferable by a
participating employee other than by will or the laws of descent and
distribution, and are exercisable during the employee's lifetime only by the
employee.

14. Application of Funds. All funds received or held by the Company under this
Plan may be combined with other corporate funds and may be used for any
corporate purpose.

15. Adjustment in Case of Changes Affecting Common Stock. In the event of a
subdivision of outstanding shares of Common Stock, or the payment of a dividend
in Common Stock, the number of shares approved for this Plan, and the share
limitation set forth in Section 9, shall be increased proportionately, and such
other adjustment shall be made as may be deemed equitable by the Board or the
Committee. In the event of any other change affecting the Common Stock, such
adjustment shall be made as may be deemed equitable by the Board or the
Committee to give proper effect to such event.

16. Merger. If the Company shall at any time merge or consolidate with another
corporation and the holders of the capital stock of the Company immediately
prior to such merger or consolidation continue to
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hold at least 80% by voting power of the capital stock of the surviving
corporation ("Continuity of Control"), the holder of each Option then
outstanding will thereafter be entitled to receive at the next Exercise Date
upon the exercise of such Option for each share as to which such Option shall be
exercised the securities or property that a holder of one share of the Common
Stock was entitled to upon and at the time of such merger or consolidation, and
the Board or the Committee shall take such steps in connection with such merger
or consolidation as the Board or the Committee shall deem necessary to assure
that the provisions of Section 15 shall thereafter be applicable, as nearly as
reasonably may be, in relation to the said securities or property as to which
such holder of such Option might thereafter be entitled to receive thereunder.

      In the event of a merger or consolidation of the Company with or into
another corporation that does not involve Continuity of Control, or of a sale of
all or substantially all of the assets of the Company while unexercised Options
remain outstanding under the Plan, (a) subject to the provisions of clauses (b)
and (c), after the effective date of such transaction, each holder of an
outstanding Option shall be entitled, upon exercise of such Option, to receive
in lieu of shares of Common Stock, shares of such stock or other securities as
the holders of shares of Common Stock received pursuant to the terms of such
transaction; or (b) all outstanding Options may be cancelled by the Board or the
Committee as of a date prior to the effective date of any such transaction and
all payroll deductions shall be paid out to the participating employees; or (c)
all outstanding Options may be cancelled by the Board or the Committee as of the
effective date of any such transaction, provided that notice of such
cancellation shall be given to each holder of an Option, and each holder of an
Option shall have the right to exercise such Option in full based on payroll
deductions then credited to his account as of a date determined by the Board or
the Committee, which date shall not be less than ten days preceding the
effective date of such transaction.

17. Amendment of the Plan. The Board may at any time, and from time to time,
amend this Plan in any respect, except that (a) if the approval of any such
amendment by the stockholders of the Company is required by Section 423 of the
Code, such amendment shall not be effected without such approval, and (b) in no
event may any amendment be made that would cause the Plan to fail to comply with
Section 423 of the Code.

18. Insufficient Shares. In the event that the total number of shares of Common
Stock specified in elections to be purchased under any Offering plus the number
of shares purchased under previous Offerings under this Plan exceeds the maximum
number of shares issuable under this Plan, the Board or the Committee will allot
the shares then available on a pro rata basis.

19. Termination of the Plan. This Plan may be terminated at any time by the
Board. Upon termination of this Plan all amounts in the accounts of
participating employees shall be promptly refunded.

20. Governmental Regulations. The Company's obligation to sell and deliver
Common Stock under this Plan is subject to listing on a national stock exchange
or quotation on the Nasdaq National Market (to the extent the Common Stock is
then so listed or quoted) and the approval of all governmental authorities
required in connection with the authorization, issuance or sale of such stock.

21. Governing Law. The Plan shall be governed by Massachusetts law except to the
extent that such law is preempted by federal law.

22. Issuance of Shares. Shares may be issued upon exercise of an Option from
authorized but unissued Common Stock, from shares held in the treasury of the
Company, or from any other proper source.

23. Notification upon Sale of Shares. Each employee agrees, by entering the
Plan, to promptly give the Company notice of any disposition of shares purchased
under the Plan where such disposition occurs within two years after the date of
grant of the Option pursuant to which such shares were purchased.
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24. Withholding. Each employee shall, no later than the date of the event
creating the tax liability, make provision satisfactory to the Board for payment
of any taxes required by law to be withheld in connection with any transaction
related to Options granted to or shares acquired by such employee pursuant to
the Plan. The Company may, to the extent permitted by law, deduct any such taxes
from any payment of any kind otherwise due to an employee.

25. Effective Date and Approval of Stockholders. The Plan shall take effect upon
the closing of the first sale of shares of Common Stock in a firm commitment
underwriting, subject to approval by the stockholders of the Company as required
by Section 423 of the Code, which approval must occur within twelve months of
the adoption of the Plan by the Board.

                              Amended by the Board of Directors as of July 2005
                              and October 25, 2005