<PAGE>   1
                                                                   EXHIBIT 10.11


                                     -62-
<PAGE>   2


                         EXECUTIVE EMPLOYMENT AGREEMENT

THIS EXECUTIVE EMPLOYMENT AGREEMENT ("Agreement") is effective as of the
4th day of January, 1997 ("Effective Date"), and is entered into this 4th day
of March, 1997, by and between HARBINGER CORPORATION ("Company"), a Georgia
corporation, and C. TYCHO HOWLE ("Employee"), an individual.  For and in
consideration of the mutual covenants described below, the parties hereby agree
as follows:

1.       Employment.     Company agrees to employ or continue to employ
Employee, and Employee agrees to accept and continue such employment, upon the
following terms and conditions.

2.       Duties.

   a.  Employee shall assume the responsibilities and perform the duties
specified in Exhibit A ("Duties"). Employee agrees to devote reasonable work
time and energy to the furtherance of the business of Company consistent with
the Duties and shall not during the term hereof work or perform services in any
advisory or other capacity (other than as a member of the Board of Directors or
Board of Advisors of an entity which is not competitive with the Company) for
any individual, firm, company, or corporation other than for Company without
Company's prior written consent.

   b.  Employee shall serve on the Company's Board of Directors (the "Board")
if elected by the Company's shareholders to serve in such capacity.

   c.  This Agreement may be supplemented from time to time by rules and
regulations of employment issued by Company, including, without limitation,
such rules and regulations described in the Company employee handbook, and
Employee agrees to adhere to these rules and regulations.

3.       Compensation.

   A.  ANNUAL SALARY.  Employee's annual salary ("Annual Salary") for
commencing as of April 1, 1997 shall be Two- Hundred and Twenty Thousand
Dollars ($220,000.00), payable in accordance with the Company's standard
payment terms.  The amount of  any Annual Salary increases in subsequent years
shall be determined by the Compensation Committee ("Committee") or the Board in
its sole discretion.

   B.  ANNUAL BONUS.  Employee's annual bonus ("Annual Bonus") for 1997 shall
be fifty percent (50%) of the 1997 Annual Salary, payable in accordance with
Employee's satisfactory fulfillment of the objectives as established and
determined by the Committee or the Board. Any future Annual Bonus(es) in
subsequent years shall be determined by the Committee or the Board.

   C.  BENEFITS.  Employee shall be entitled to receive the same employee
benefits as made available by Company to its Chief Executive Officer.

4.       STOCK OPTION.     The Company acknowledges that Employee has received
an option to purchase One Hundred Thousand (100,000) shares of common stock of
the Company (the "Option") (150,000 shares as of the January 31, 1997 stock
split) on the terms and subject to the conditions set forth in the Stock Option
Agreement, attached hereto as Exhibit C.


5.       Term.  The term of this Agreement (the "Term") shall commence on the
Effective Date and shall remain in full force and effect for four (4) years
thereafter, unless sooner terminated as provided in Section 9 below.  Upon the
Effective Date, the previously executed Employment Agreement between Company
and Employee dated March 7, 1994 shall be deemed to have terminated
automatically and shall thereafter be of no further force or effect, and this
Agreement shall supersede all prior agreements, arrangements and understandings
with respect to the subject matter hereof, except as set forth in Section
13(b).

6.       OWNERSHIP.  For purposes of this Agreement, "Work Product" shall mean
the data, materials, documentation, computer programs, inventions (whether or
not patentable), and all works of authorship, including all worldwide rights
therein under patent, copyright, trade secret, confidential information, or
other property right, created or developed in whole or in part by Employee,
whether prior to or after the Effective Date, while retained or employed by
Company (whether developed during work hours or not).  All Work Product shall
be considered work made for hire by Employee and owned by Company.  If any of
the Work Product may not, by operation of law or otherwise, be considered work
made for hire by Employee for Company, or if ownership of all right, title, and
interest of the intellectual property rights therein shall not otherwise vest
exclusively in Company, Employee hereby assigns to Company, and upon the future
creation thereof automatically assigns to Company, without further
consideration, the ownership of all Work Product.  Company shall have the right
to obtain and hold in its own name copyrights, patents, registrations, and any
other protection available in the Work Product.  Employee agrees to perform,
during or after Employee's employment, such further acts as may be necessary or
desirable to transfer, perfect, and defend Company's ownership of the Work


                                     -63-
<PAGE>   3

Product that are reasonably requested by Company.

7.       LICENSE.     To the extent any materials other than Work Product are
contained in the materials Employee delivers to Company or Company's customers
("Licensed Materials"), Employee grants to Company an irrevocable,
nonexclusive, worldwide, royalty-free license to: (i) use and distribute
(internally or externally) copies of, and prepare derivative works based upon,
the Licensed Materials and derivative works thereof, and (ii) authorize others
to do any of the foregoing.

8.       NONDISCLOSURE OF PROPRIETARY INFORMATION.

   a.    As used herein, "Trade Secrets" means information constituting a trade
secret within the meaning of Section 10- 1-761(4) of the Georgia Trade Secrets
Act of 1990, including all amendments hereafter adopted.  As used herein,
"Confidential Information" means information, other than Trade Secrets, that is
of value to its owner and is treated as confidential.  "Proprietary
Information" means, collectively, Confidential Information and Trade Secrets.

   b.    Company may disclose to Employee certain Proprietary Information.
Employee acknowledges and agrees that the Proprietary Information of Company is
the sole and exclusive property of Company (or a third party providing such
information to Company) and that Company owns all worldwide copyrights, trade
secret rights, confidential and proprietary information rights, and all other
property rights therein.

   c.    Employee acknowledges and agrees that the disclosure of the
Proprietary Information of Company to Employee does not confer upon Employee
any license, interest or rights of any kind in or to the Proprietary
Information.

   d.    Employee agrees to use the Proprietary Information solely for the
benefit of Company.  Except in the performance of services for Company,
Employee will hold in confidence and not use, reproduce, distribute, transmit,
reverse engineer, decompile, disassemble, or transfer, directly or indirectly,
in any form, by any means, or for any purpose, the Proprietary Information of
Company or any portion thereof communicated, discussed, delivered or made
available by Company to or received by Employee, whether orally or in written
form, without the prior written consent of Company.  Employee shall notify
Company immediately upon discovery of any unauthorized use or disclosure of the
Proprietary Information.

   e.    Employee acknowledges that its obligations under this Agreement with
regard to the Trade Secrets of Company remain in effect for as long as such
information shall remain a trade secret under applicable law.  Employee
acknowledges that its obligations with regard to the Confidential Information
of Company shall remain in effect while Employee is retained by Company to
perform the Duties and for three (3) years thereafter.  The foregoing
obligations shall not apply if and to the extent that:  (a) Employee
establishes that the information communicated was already known to Employee,
without obligation to keep it confidential, at the time of its receipt from
Company; (b) Employee establishes that the information communicated was
received by Employee in good faith from a third party lawfully in possession
thereof and having no obligation to keep such information confidential; or (c)
Employee establishes that the information communicated was publicly known at
the time of its receipt by Employee or has become publicly known other than by
a breach of this Agreement or other action by Employee.

   f.  The terms of this Agreement and the relationship between Company and
Employee shall be subject to the obligations of nondisclosure herein, except to
the extent that disclosure thereof is required by  law or regulation.

9.       TERMINATION.     The parties agree that Employee's term of employment
may be terminated at any time, for any reason or for no reason, with cause or
without cause (as defined below), by Company or Employee.

   A.    TERMINATION WITH CAUSE.  The parties agree that Employee's employment
may be terminated at any time with notice by Company for cause ("Termination
With Cause") under any one or more of the following events:

                 (i)      Employee's knowing and willful misconduct with
         respect to the business and affairs of the Company;

                 (ii)     Any material violation by Employee of any policy of
         the Company relating to ethical business conduct or practices or
         fiduciary duties of a senior executive;


                                     -64-
<PAGE>   4

                  (iii)   Knowing and willful material breach of any provision
         of this Agreement which is not remedied within thirty (30) days after
         Employee's receipt of notice thereof;

                 (iv)     Employee's commission of a felony or an illegal act
         involving moral turpitude or fraud or Employee's dishonesty which may
         reasonably be expected to have a material adverse effect on the
         Company; and/or

                 (v)      Failure to comply with reasonable directives of the
         Board which are consistent with the Duties, if not remedied within
         thirty (30) days after Employee's receipt of notice thereof.

   B.    TERMINATION WITHOUT CAUSE.  "Termination Without Cause" means any
termination of employment by the Company which is not "Termination With Cause"
as defined above.  A resignation or voluntary departure from Company by
Employee or his death shall not be deemed Termination Without Cause under this
Agreement.

   C.    SEVERANCE.  In the event that Employee's employment is Terminated
Without Cause by Company at any time (other than at the expiration of the
Term), Company shall pay to Employee the severance pay equal to Employee's
Annual Salary at the then current rate for a period equal to the remainder of
the then current Term ("Severance Period").  The severance pay shall be payable
to Employee in accordance with the Company's standard pay periods and shall be
subject to all applicable withholdings, or, in the Company's sole discretion,
in a lump sum equal to the Annual Salary for the period equal to the remainder
of the current Term, discounted to  its present value as reasonably determined
by the Board.

   D.    POST TERMINATION OBLIGATIONS.  Upon termination of employment for any
reason, Employee shall return immediately to Company all documents, property,
and other records of Company, and all copies thereof, and all Work Product
within Employee's possession, custody or control, including but not limited to
any materials containing any Trade Secrets or Confidential Information or any
portion thereof.

10.      Customer Non-Solicitation.     The relationships made or enhanced in
the course of Employee's employment with the Company belong to Company.  During
Employee's employment with Company and for the period of one (1) year after
termination of Employee's employment with Company for any reason or the
Severance Period, whichever is longer (the "Limitation Period"), Employee shall
not contact, solicit or attempt to solicit, on Employee's own behalf or on
behalf of any other person or entity, any customer or prospective customer of
Company with whom Employee had contact in the two (2) years prior to the end of
Employee's employment with Company ("Restrictive Period") with a view to
offering, providing, selling or licensing during the Limitation Period any
program, product or service that is competitive with the Company's business as
defined in Exhibit B ("Company Business").

11.      EMPLOYEE NON-SOLICITATION.     During the Limitation Period, Employee
agrees not to call upon, solicit, recruit, or assist others in calling upon,
recruiting or soliciting any person who is or was an employee of Company during
the Restrictive Period, for the purpose of having such person work in any other
corporation, association, entity, or business that is competitive with the
Company Business.

12.      NONCOMPETITION.     DURING THE LIMITATION PERIOD, EMPLOYEE AGREES
THAT, WITHOUT THE PRIOR WRITTEN CONSENT OF COMPANY, EMPLOYEE SHALL NOT PERFORM
THE DUTIES SPECIFIED ON EXHIBIT A and performed by Employee during the
Restrictive Period for any person or entity competing with the Company Business
in the territory defined in EXHIBIT B ("Territory"), provided that Company is
still engaged in the Company Business.  The parties agree and acknowledge that:
(i) the periods of restriction and Territory of restriction contained in this
Agreement are fair and reasonable in that they are reasonably required for the
protection of Company and that the Territory is the area in which Employee
shall perform (or currently performs) services for Company; and (ii) by having
access to information concerning employees and actual or prospective customers
of Company, Employee shall obtain a competitive advantage as to such parties.
If, however, for any reason any court determines that the restrictions in
Sections  10 through 12 are not reasonable or that consideration is inadequate,
then such restrictions shall be interpreted, modified or re-written to include
as much of the duration, scope and geographic area in this section as will
render such restrictions valid and enforceable.


                                     -65-
<PAGE>   5

13.      INDEMNIFICATION.

      A.         BY EMPLOYEE.  Employee shall indemnify and hold harmless
Company, any affiliated corporation, and their respective shareholders,
directors, officers, agents, and employees, from and against any and all
liability, including payment of attorneys' fees, arising directly or indirectly
from a violation of Section 13.

      B.         BY COMPANY.  Company shall indemnify and hold harmless
Employee in accordance with the indemnification obligations as set forth in
Article IX, Section 2 of the  Company's Amended and Restated Bylaws dated April
29, 1995, and the previously executed Indemnification Agreement between Company
and Employee.

14.      EQUITABLE RELIEF.    The parties to this Agreement acknowledge that a
breach by Employee of any of the terms or conditions of this Agreement will
result in irrevocable harm to Company and that the remedies at law for such
breach may not adequately compensate Company for damages suffered.
Accordingly, Employee agrees that in the event of such breach, Company shall be
entitled to injunctive relief or such other equitable remedy as a court of
competent jurisdiction may provide.  Nothing contained herein will be construed
to limit Company's right to any remedies at law, including the recovery of
damages for breach of this Agreement.

15.      SEVERABILITY.     If any provision or part of any provision of this
Agreement is held invalid or unenforceable by a court of competent
jurisdiction, such holding shall not affect the enforceability of any other
provisions or parts thereof, and all other provisions and parts thereof shall
continue in full force and effect.

16.      ARBITRATION.      Any controversy or claim arising out of or relating
to this Agreement or the breach thereof (other than disputes with respect to
alleged violations of the covenants contained in Sections 10, 11, and 12, and
the Company's pursuit of the remedies described in Section 15 in connection
therewith) shall be settled by arbitration in Atlanta, Georgia.  In such case,
both parties agree to the appointment of three (3) arbitrators, with one
arbitrator selected by each party, and the third selected by the American
Arbitration Association ("AAA").  The arbitration shall be conducted in
Atlanta, Georgia in accordance with the Commercial Arbitration Rules,
regulations and procedures of the AAA.  The judgment upon the award rendered
may be entered in any court having jurisdiction thereof.  The parties shall be
free to pursue any remedy before the arbitration tribunal that they shall be
otherwise permitted to pursue in a court of competent jurisdiction, and the
decision of the arbitration panel shall be final and binding on both parties.

17.      MISCELLANEOUS.    This Agreement shall not be amended or modified
except by a writing executed by both parties.  This Agreement shall be binding
upon and inure to the benefit of Company and its successors and assigns.  Due
to the personal nature of this Agreement, Employee shall not have the right to
assign Employee's rights or obligations under this Agreement without the prior
written consent of company.  This agreement shall be governed by the laws of
the state of Georgia without regard to its rules governing conflicts of law.
This Agreement and the attached Exhibits represent the entire understanding of
the parties concerning the subject matter hereof and supersede and terminate
all prior communications, agreements and understandings, whether oral or
written, relating to the subject matter hereof.  All communications required or
otherwise provided under this Agreement shall be in writing and shall be deemed
given when delivered to the address provided below such party's signature (as
may be amended by notice from time to time), by hand, by courier or express
mail, or by registered or certified united states mail, return receipt
requested, postage prepaid.  The exhibits attached hereto are incorporated
herein by this reference.

   IN WITNESS WHEREOF, the parties hereto have executed this Agreement and
affixed their hands and seals effective as of the date first above written.

<TABLE>
<S>                                                <C>
COMPANY:   HARBINGER CORPORATION
                                                   EMPLOYEE:   C. TYCHO HOWLE

By:  /s/ David T. Leach
Title:                                             Signature   /s/ C. Tycho Howle
      ------------------------------                         --------------------
Date:                                              Date:
      ------------------------------                     -----------------------------

                                                   Address:  905 Reds Ridge Court, N.W.
Address:  1055 Lenox Park Boulevard                          Atlanta, Georgia 30327
          Atlanta, Georgia 30319
</TABLE>




                                     -66-