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                                                          Exhibit 10.20


                              CONSULTANCY AGREEMENT

This CONSULTING AGREEMENT (this "Agreement"), is made and entered into this
first day of September 1997 (the "Effective Date"), by and between ISOCOR, a
California Corporation, having a principal place of business at 3420 Ocean Park
Blvd., Suite 2010, Santa Monica, California USA 90405-3306 (hereinafter
"ISOCOR"), and Consultant, Cagan Co Inc., a C corporation registered under the
laws of California, with offices at 1170 Coast Village Road, Suite 212, Santa
Barbara, CA 93108 (hereinafter "Consultant").

ISOCOR is desirous of securing the services of a Consultant skilled and
experienced in high technology disciplines of strategy, sales, marketing,
services and distribution.

NOW, THEREFORE, the parties agree as follows:

1.00    DEFINITIONS

1.10    "CLIENT" shall mean any third party with whom ISOCOR contracts or
        negotiates to supply products, consulting or software support services,
        whether solely or in part.

1.20    "PROJECT COMMENCEMENT" shall mean the date by which the Consultant shall
        begin consulting at an ISOCOR location, Client's location, some other
        location or via some other medium.

1.30    "WORK ORDER" shall mean a writing signed by each party which includes at
        a minimum the name of the client to be worked for, if any, the projected
        start date of the project, an estimate of the total hours to be worked
        for the project, and a brief outline of the tasks involved in completing
        the project. The initial Work Order is attached hereto as Exhibit A.

2.00    TERM AND TERMINATION

2.10    TERM. This Agreement will become effective on the date first shown above
        and will continue in effect for one year, and shall be automatically
        renewed for a second year unless either party gives notice in writing at
        least ten (10) days in advance of the renewal date.

2.20    TERMINATION. This Agreement can be terminated by either party in writing
        with fourteen (14) days notice after the initial one year term. If this
        Agreement is terminated, ISOCOR's sole obligation shall be to pay
        Consultant the amount due for the Services completed as of the effective
        date of termination. Termination of a Work Order at ISOCOR's discretion,
        as set forth following in Section 4.31, will not serve to terminate this
        Agreement unless the Agreement is also expressly terminated in the same
        or separate writing as set forth above. Notwithstanding the foregoing,
        the initial Work Order incorporated herein as Exhibit A shall not be
        terminated by ISOCOR except in the event of cause or material breach of
        this Agreement by Consultant.

2.30    SURVIVAL. In the event of any termination of this Agreement, Section 6
        hereof shall survive and continue in effect.

3.00    INDEPENDENT CONTRACTOR STATUS

3.10    INTENTION OF PARTIES. It is the intention of the parties that Consultant
        be an independent contractor and not an employee, agent, joint venturer,
        or partner of ISOCOR. Nothing in this Agreement shall be interpreted or
        construed as creating or establishing the relationship of employer and
        employee between ISOCOR and either Consultant or any employee or agent
        of Consultant. Consultant shall have no right or power to enter into any
        contract or commitment on behalf of ISOCOR.

3.20    LIMITED EXCLUSIVITY. Consultant shall retain the right to perform work
        for others during the terms of this Agreement, except as noted in
        Section 3.21. ISOCOR shall retain the right to cause work of the same or
        a different kind to be performed by its own personnel or other
        contractors during the term of this Agreement.

        3.21 During the term hereof, and for a period of two years following
        termination of this agreement, Consultant shall not solicit ISOCOR's
        Clients for consultancy or other services regarding any products with
        similar functions, such as Internet- or X.400-based messaging services,
        as those available from ISOCOR, except as specifically agreed to
        beforehand in writing by ISOCOR.


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4.00    SERVICES TO BE PERFORMED BY CONSULTANT

4.10    WORK ORDERS. ISOCOR will advise Consultant of upcoming consulting
        projects at least one week in advance of the date for Project
        Commencement. The parties shall agree upon a detailed description of
        services to be provided. ISOCOR will then forward to Consultant a Work
        Order. Consultant is only authorized to provide services under this
        agreement pursuant to signed Work Orders. ISOCOR shall have no liability
        to Consultant for any services performed which were not authorized by a
        written and signed Work Order.

4.20    RETURN OF DATA. Upon termination of this Agreement, Consultant shall
        return to ISOCOR all materials supplied to it and all materials produced
        and acquired by Consultant in the course of rendering services under
        this Agreement.

4.40    METHOD OF PERFORMING SERVICES. Consultant will reasonably determine the
        method, details, and means of performing the work to be carried out by
        it for ISOCOR's clients. ISOCOR shall be entitled to exercise a broad
        general power of supervision and control over the results of work
        performed by Consultant to ensure satisfactory performance. This power
        of supervision shall include the right to inspect, stop work, make
        suggestions or recommendations as to the details of the work, and
        request modifications to the scope of a project for its Clients.

        4.41 ISOCOR's power of supervision shall also include the right to stop,
        or pause any work on any Work Order being done by Consultant for
        ISOCOR's Clients. Any such action by ISOCOR shall be in writing, and
        ISOCOR and its Clients' liability for services rendered shall be limited
        on any such stopped, paused or terminated Work Order to work performed
        by Consultant prior to receipt of the request to stop, pause or
        terminate.

5.00    COMPENSATION

5.10    COMPENSATION AND BILLING FOR SERVICES. Compensation to Consultant for
        services Consultant has performed shall be as set out in the applicable
        Work Order. Consultant's fee shall include and Consultant shall be
        responsible for the payment of all taxes imposed by any governmental
        agency of any kind which are attributable to the compensation it
        receives. In no event shall ISOCOR be liable to Consultant for services
        rendered on a Work Order in the face of non-payment or suit by Client
        for poor work, incomplete services or other harm or damage caused by
        Consultant and not the fault of ISOCOR.

5.20    WORK REPORTS. Consultant shall submit Work Reports to ISOCOR on a
        calendar month basis for the services furnished and other expenses
        incurred hereunder. Each Work Report will provide a breakdown and
        distribution of services performed and expense items.

5.30    DATE FOR PAYMENT OF COMPENSATION. ISOCOR shall pay Consultant for its
        services as set out in the applicable Work Order, or, if not specified,
        within fifteen (15) days from the end of each calendar month for
        services completed in that month.

5.4     EXPENSES. Except as otherwise agreed in this Agreement, Consultant shall
        be responsible for all costs and expenses incident to the performance of
        services for ISOCOR, including all costs incurred by Consultant to do
        business. In the event, telephone, travel, communication or on-site room
        and board expenses are incurred by Consultant, ISOCOR agrees to pay
        these expenses in accordance with ISOCOR's corporate policy attached
        hereto as Exhibit B.

6.00    INTELLECTUAL PROPERTY RIGHTS

6.10    CONFIDENTIAL INFORMATION. Consultant agrees that all Confidential
        Information which it may acquire from ISOCOR or from ISOCOR's employees
        or associates, shall be regarded as strictly confidential and held in
        trust solely for the benefit of ISOCOR. Consultant shall not use or
        directly or indirectly disclose such Confidential Information to any
        other party without the written consent of ISOCOR during the term of and
        for three years following the termination of this Agreement.
        Confidential Information includes, for example, trade secrets, data,
        know-how, developments, designs, techniques, marketing plans,
        promotional ideas, strategies, forecasts, new products, licenses, costs,
        customer and supplier lists, specifications, computer software programs,
        manuals, and any information marked "Confidential" by ISOCOR. These
        restrictions shall not be construed to apply to (1) information
        generally available to the public; (2) information released by ISOCOR
        generally without restriction; (3) information independently developed


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        or acquired by Consultant without reliance in any way on other protected
        information of ISOCOR; or (4) information approved for the use and
        disclosure of Consultant. Neither party shall furnish to the other party
        any Confidential Information which it does not have the right to furnish
        and shall defend and indemnify the receiving party against any claim or
        liability resulting from breach of such obligation.

6.20    OWNERSHIP OF WORK PRODUCT. All copyrights, patents, trade secrets, or
        other intellectual property rights associated with any ideas, concepts,
        techniques, inventions, processes, or works of authorship developed or
        created by Consultant during the course of performing ISOCOR's work
        (collectively, the "Work Product") shall belong exclusively to ISOCOR
        and shall, to the extent possible, be considered a work made for hire
        for ISOCOR within the meaning of Title 17 of the United States Code.
        Consultant automatically assigns at the time of creation of the Work
        Product, without any requirement of further consideration, any right,
        title, or interest it may have in such Work Product, including any
        copyrights or other intellectual property rights pertaining thereto.
        Upon request of ISOCOR, Consultant shall take such further actions
        including execution and delivery of instruments of conveyance, as may be
        appropriate to give full and proper effect to such assignment.

6.30    RESIDUAL RIGHTS. Notwithstanding anything to the contrary herein,
        Consultant shall be free to use and employ its general skills, know-how,
        and expertise, and to use, disclose, and employ any generalized ideas,
        concepts, know-how, methods, techniques, or skills gained or learned
        during the course of any assignment, so long as it acquires and applies
        such information without disclosure of any confidential or proprietary
        information of ISOCOR and without any unauthorized use or disclosure of
        Work Product.

7.00    CONSULTANT PERSONNEL

7.10    COMPENSATION OF CONSULTANT'S PERSONNEL. Consultant shall bear sole
        responsibility for payment of compensation to and taxes for any of its
        personnel or agents performing services hereunder. Consultant shall pay
        and report, for itself and any such personnel, all applicable taxes due
        on amounts paid to it hereunder. Consultant shall bear sole
        responsibility for any liability, health or disability insurance,
        retirement benefits, or other welfare or pension benefits (if any) to
        which itself and any of its personnel may be entitled. Consultant agrees
        to defend, indemnify, and hold harmless ISOCOR, ISOCOR's officers,
        directors, employees, and agents, and the administrators of ISOCOR's
        benefit plans from and against any claims, liabilities, or expenses
        relating to such compensation, tax, insurance, or benefit matters;
        provided that ISOCOR shall promptly notify Consultant of each such claim
        when and as it comes to ISOCOR's attention, cooperate with Consultant in
        the defense and resolution of such claim, and not settle or otherwise
        dispose of such claim without Consultant's prior written consent, such
        consent not to be unreasonably withheld.

7.20    WORKERS' COMPENSATION. Notwithstanding any other workers' compensation
        or insurance policies maintained by ISOCOR, Consultant shall procure and
        maintain workers' compensation coverage sufficient to meet the statutory
        requirements of every state where Consultant's personnel assigned to
        ISOCOR's work are located.

7.30    CONSULTANT'S AGREEMENTS WITH PERSONNEL. Consultant shall obtain and
        maintain in effect written agreements with each of its personnel, if
        any, who participate in any of the ISOCOR's work hereunder. Such
        agreements shall contain terms sufficient for Consultant to comply with
        all provisions of this Agreement.

7.40    STATE AND FEDERAL TAXES. As neither Consultant nor its personnel are
        ISOCOR's employees, ISOCOR shall not take any action or provide
        Consultant's personnel with any benefits or commitments inconsistent
        with any of such undertakings by Consultant.
        In particular:

        1.  ISOCOR will not withhold FICA (Social Security) from Consultant's
            payments.

        2.  ISOCOR will not make state or federal unemployment insurance
            contributions on behalf of Consultant or its personnel.

        3.  ISOCOR will not withhold state and federal income tax from payment
            to Consultant.

        4.  ISOCOR will not make disability insurance contributions on behalf of
            Consultant.

        5.  ISOCOR will not obtain workers' compensation insurance on behalf of
            Consultant or its personnel.

8.00    GENERAL PROVISIONS


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8.10    NOTICES. Any notices to be given hereunder by either party to the other
        may be effected either by personal delivery in writing or by mail,
        registered or certified, postage prepaid with return receipt requested.
        Mailed notices shall be addressed to the parties at the addresses
        appearing in the introductory paragraph of this Agreement, but each
        party may change such address by written notice in accordance with this
        paragraph. Notices delivered personally will be deemed communicated as
        of actual receipt. Mailed notices will be deemed communicated as of two
        days after mailing.

8.30    ENTIRE AGREEMENT OF THE PARTIES. This Agreement supersedes any and all
        agreements, either oral or written, between the parties hereto with
        respect to the rendering of Services by Consultant for ISOCOR and
        contains all the covenants and agreements between the parties with
        respect to the rendering of such services in any manner whatsoever. Each
        party to this agreement acknowledges that no representations,
        inducements, promises, or agreements, orally or otherwise, have been
        made by any party, or anyone acting on behalf of any party, that are not
        embodied herein, and that no other agreement, statement, or promise not
        contained in this agreement shall be valid or binding. Any modification
        of this agreement will be effective only if it is in writing signed by
        the party to be charged. Notwithstanding the foregoing, the parties
        specifically acknowledge that the Confidentiality Agreement dated August
        22, 1997 between the parties shall remain in full force and effect.

8.40    PARTIAL INVALIDITY. If any provision in this agreement is held by a
        court of competent jurisdiction to be invalid, void, or unenforceable,
        the remaining provisions will nevertheless continue in full force
        without being impaired or invalidated in any way.

8.50    GOVERNING LAW. This Agreement will be governed by and construed in
        accordance with the laws of the State of California.

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed
by their respective duly authorized representative. All copies of this
Amendment, signed by both parties, shall be deemed originals.

ISOCOR                                  CONSULTANT


Signed: /s/ JANINE BUSHMAN              Signed: /s/ DENNIS J. CAGAN
        ----------------------------            --------------------------------

Name:   JANINE BUSHMAN                  Name:   DENNIS J. CAGAN
        ----------------------------            --------------------------------

Title:  CFO                             Title:  PRESIDENT
        ----------------------------            --------------------------------

Date:   8/30/97                         Date:   8-30-97
        ----------------------------            --------------------------------


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                                    EXHIBIT A
                       WORK ORDER #1 - INITIAL WORK ORDER


                   
CONTRACTOR
PERSONNEL:            DENNIS CAGAN

DURATION OF
PROJECT               September 1, 1997 - August 31, 1998

COMPENSATION:         $6,000 per calendar month; plus contingent compensation of
                      up to $6,000 per calendar month, based upon the Executive
                      Bonus Program as approved by the Board of Directors of
                      ISOCOR, which Program for the period September 1, 1997
                      through December 31, 1997 is attached hereto as Exhibit B.
                      ISOCOR reserves the right to change the Executive Bonus
                      Program at the discretion of the Board of Directors.

EXPENSES              Minimal telephone, travel and living directly incurred in
                      performance of this Work Order, and in accordance with
                      ISOCOR reimbursement policies

SCOPE OF WORK:        1.25 days per week shall be exclusively devoted to ISOCOR 
                      strategy, sales, marketing, services and distribution.


Work Order Approved by ISOCOR :    /s/ JANINE BUSHMAN     Date: 8-30-97
                                  ---------------------         ----------------

Work Order Accepted by Consultant: /s/ DENNIS CAGAN       Date: 8-30-97
                                  ---------------------         ----------------


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                       Exhibit B - Executive Bonus Program
              Period Covering September 1, 1997 - December 31, 1997


Participation in this Program for the second calendar half of 1997 is based upon
the weighted actual achievement of consolidated revenues and net income/(loss)
against planned levels of consolidated revenues and net income/(loss) of ISOCOR.
The Program provides for linear interpolation between the floor (at 85% weighted
performance) and 100% weighted performance, with the same rate beyond 100%
weighted performance. Calculations of contingent compensation will be made on a
calendar six month basis.

The weighted factors used in the Program are:



        Driver                                              Weight
        ------                                              ------
                                                         
          Revenue                                            60%
          Net Income/(Loss)  (post bonus)                    40%


        Contingent Compensation Opportunity

          At 100% weighted performance - $24,000

          At 85% floor weighted performance - $1,200

                (Below 85% weighted performance no contingent compensation is
                payable)

          At 112% weighted performance - $42,240

The goals for performance for the second calendar six months of 1997 are as
follows and exclude the impact of any acquisition activity ISOCOR may complete
in 1997:



                                      Second Half 1997
                                      ----------------
                                           
                   Revenue              $14,600,000
                   Net Loss              $1,193,000



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                                    EXHIBIT A

                                 WORK ORDER #2:
           PURSUANT TO CONSULTANCY AGREEMENT SIGNED SEPTEMBER 1, 1997
                     (CANCELS AND SUPERSEDES WORK ORDER #1)


                   
CONTRACTOR:           DENNIS CAGAN

DURATION OF           February 9, 1998 to August 31, 1998
PROJECT

COMPENSATION:         $3,000 per calendar month; plus contingent compensation of
                      up to $3,000 per calendar month, based upon the Executive
                      Bonus Program as approved by the Board of Directors of
                      ISOCOR (ISOCOR reserves the right to change the Executive
                      Bonus Program at the discretion of the Board of
                      Directors).

EXPENSES              minimal telephone, travel, and living expenses directly
                      incurred in performance of this Work Order in accordance
                      with ISOCOR's reimbursement policies (receipts must
                      accompany any invoice)

SCOPE OF WORK:        1 day every 2 weeks shall be exclusively devoted to ISOCOR
                      strategy, sales, marketing, professional services issues,
                      and distribution development; such work shall be performed
                      in ISOCOR's Santa Monica, California office unless
                      otherwise agreed 


THIS WORK ORDER #2 CANCELS AND SUPERSEDES WORK ORDER #1.


Work Order Approved by ISOCOR:     [SIG]                  Date: 2/11/98
                                   ----------------------       ----------------

Work Order Accepted by Consultant: [SIG]                  Date: 2-11-98
                                   ----------------------       ----------------


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