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                                                                   Exhibit 10(k)
                                                                                
                         EXECUTIVE SEVERANCE AGREEMENT
                         -----------------------------
                                        
     This EXECUTIVE SEVERANCE AGREEMENT (the "Agreement"), is made as of May 19,
1997 by and between ADVO, Inc. (the "Company") and  A. Brian Sanders (the
"Executive").

                                   RECITALS:
                                   -------- 

     A.  The Executive is an executive of the Company and has made and is
expected to continue to make major contributions to the short-and long-term
profitability, growth, and financial strength of the Company;

     B.  The Company recognizes that the possibility of a Change of Control (as
hereafter defined) exists;

     C.  The Company desires to assure itself of both present and future
continuity of its management and desires to establish certain severance benefits
for key executive officers of the Company, including the Executive, applicable
in the event of a Change of Control; and
 
     D.  The Company wishes to aid in assuring that such executives are not
practically disabled from discharging their duties in respect of a proposed or
actual transaction involving a Change of Control.

     NOW, THEREFORE, the Company and the Executive agree as follows:

     1.  Certain Defined Terms:  In addition to terms defined elsewhere herein,
         ---------------------                                                  
the following terms have the following meanings when used in this Agreement with
initial capital letters:

         (a) "Affiliate" means (i) each entity in which the Company, alone or
together with one or more other Affiliates of the Company, owns not less than
80% of the then outstanding voting securities or, for any entity that is not a
corporation, at least 80% of the then-outstanding capital interests of such
entity and (ii) any additional entity which is deemed by action of the Board to
be an Affiliate for the purposes of this Agreement.

         (b) "Base Pay" means the Executive's annual aggregate fixed base salary
from the Company at the time in question.

         (c) "Board" means the Board of Directors of the Company.

         (d) "Change of Control" means the occurrence during the Term of any of
the following events:

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               (i)   The acquisition by an individual, entity or group (within
the meaning of Section 13 (d)(3) or 14 (d)(2) of the Securities Exchange Act of
1934, as amended (the "Exchange Act")), other than Warburg (a "Person") of
beneficial ownership (within the meaning of Rule 13d-3 promulgated under the
Exchange Act) of voting securities of the Company where such acquisition causes
such Person to own 30% or more of the combined voting power of the then
outstanding voting securities of the Company entitled to vote generally in the
election of directors (the "Outstanding Company Voting Securities"); provided
however, that for purposes of this Subsection (i), the following acquisitions
shall not be deemed to result in a Change of Control: (A) any acquisition
directly from the Company, (B) any acquisition by the Company, (C) any
acquisition by any employee benefit plan (or related trust) sponsored or
maintained by the Company or any corporation controlled by the Company or (D)
any acquisition by any corporation pursuant to a transaction that complies with
clauses (A), (B) and (C) of subsection (iii) below; and provided, further, that
if any Person's beneficial ownership of the Outstanding Company Voting
Securities reaches or exceeds 30% as a result of a transaction described in
clause (A) or (B) above, and such Person subsequently acquires beneficial
ownership of additional voting securities of the Company, such subsequent
acquisition shall be treated as an acquisition that causes such Person to own
30% or more of the Outstanding Company Voting Securities; or

               (ii)  Individuals who, as of the date hereof, constitute the
Board (the "Incumbent Board") cease for any reason to constitute at least a
majority of the Board; provided, however, that any individual becoming a
director subsequent to the date hereof whose election, or nomination for
election by the Company's shareholders, was approved by a vote of at least a
majority of the directors then comprising the Incumbent Board shall be
considered as though such individual were a member of the Incumbent Board, but
excluding, for this purpose, any such individual whose initial assumption of
office occurs as a result of an actual or threatened election contest with
respect to the election or removal of directors or other actual or threatened
solicitation of proxies or consents by or on behalf of a Person other than the
Board; and provided, further, that any partner, employee or representative of
Warburg proposed by Warburg to be elected to the Board shall be considered a
member of the Incumbent Board; or

               (iii) The approval by the shareholders of the Company of a
reorganization, merger or consolidation or sale or other disposition of all or
substantially all of the assets of the Company or the acquisition of assets of
another corporation ("Business Combination") or, if consummation of such
Business Combination is subject, at the time of such approval by shareholders,
to the consent of any government or governmental agency, the obtaining of such
consent (either explicitly or implicitly by consummation); excluding, however,
such a Business Combination pursuant to which (A) all or substantially  all of
the individuals and entities who were the beneficial owners of the Outstanding
Company Voting Securities immediately prior to such Business Combination
beneficially own, directly or indirectly, more than 60% of, respectively, the
then outstanding shares of common stock and the combined voting power of the
then

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<PAGE>
 
outstanding voting securities entitled to vote generally in the election of
directors, as the case may be, of the corporation resulting from such Business
Combination (including, without limitation, a corporation that as a result of
such transaction owns the Company or all or substantially all of the Company's
assets either directly or through one or more subsidiaries) in substantially the
same proportions as their ownership, immediately prior to such Business
Combination of the Outstanding Company Voting Securities, (B) no Person
(excluding any employee benefit plan (or related trust) of the Company or such
corporation resulting from such Business Combination) beneficially owns,
directly or indirectly, 30% or more of, respectively, the then outstanding
shares of common stock of the corporation resulting from such Business
Combination or the combined voting power of the then outstanding voting
securities of such corporation except to the extent that such ownership existed
prior to the Business Combination and (C) at least a majority of the members of
the board of directors of the corporation resulting from such Business
Combination were members of the Incumbent Board at the time of the execution of
the initial agreement, or of the action of the Board, providing for such
Business Combination; or

               (iv)  approval by the shareholders of the Company of a complete
liquidation or dissolution of the Company.

         (e) "Cause" means that, prior to any Termination by the Executive for
Good Reason, the Executive shall have:
 
               (i)   committed an intentional act of fraud, embezzlement, or
theft in connection with the Executive's duties or in the course of his
employment with the Company;

               (ii)  committed intentional wrongful damage to property of the
Company; or

               (iii) intentionally and wrongfully disclosed confidential
information of the Company; and any such act shall have been materially harmful
to the Company.

For the purposes of this Agreement, no act on the part of the Executive shall be
deemed "intentional" if it was due primarily to an error in judgment or
negligence, but shall be deemed "intentional" only if done by the Executive not
in good faith and without reasonable belief that the Executive's action or
omission was in the best interests of the Company.

         (f) "Date of Termination" means the date of receipt of the Notice of
Termination or any later date specified therein, as the case may be; provided,
however, that if the Executive is Terminated by the Company other than for Cause
or for disability pursuant to Section 2(a) (ii), the Date of Termination will be
the date on which the Executive receives the Notice of Termination from the
Company; and provided further,

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<PAGE>
 
if the Executive is Terminated by reason of death or disability pursuant to
Section 2(a)(i) or 2(a)(ii), the Date of Termination will be the last day of the
month in which occurs the date of death or the disability effective date, as the
case may be.

         (g) "Employee Benefits" means the perquisites, benefits and service
credit for benefits as provided under the plans and programs maintained by the
Company, including, but not limited to, plans and programs which are "employee
benefit plans" under Section 3 (3) of the Employee Retirement Income Security
Act of 1974, as amended, and any amendment or successor, to such plans or
programs (whether insured, funded or unfunded).

         (h) "Good Reason" means the occurrence of any of the events listed in
Sections 2(b)(i) through 2(b)(vii), inclusive.

         (i) "Incentive Pay" means an annual amount equal to the aggregate
annual bonus, in addition to Base Pay, made or to be made in regard to services
rendered in any calendar year or performance period pursuant to any bonus plan
of the Company.

         (j) "Notice of Termination" means a written notice which (i) indicates
the specific provision in this Agreement relied upon, (ii) sets forth in
reasonable detail the facts and circumstances claimed to provide a basis for the
Termination under the provision so indicated, and (iii) if the effective date of
the Termination is other than the date of receipt of such notice, specifies the
effective date of Termination (which date will not be more than sixty (60) days
after the giving of such notice). The failure by the Executive to set forth in
the Notice of Termination any fact or circumstance which contributes to a
showing that the Executive is entitled to the benefits intended to be provided
by this Agreement will not constitute a waiver of any right of the Executive
hereunder or otherwise preclude the Executive from later asserting such fact or
circumstance in enforcing the Executive's rights hereunder.

         (k) "Severance Period" means the period of time commencing on the date
of an occurrence of a Change of Control and continuing until the earlier of (i)
the date which is one and one-half years following the occurrence of the Change
of Control, and (ii) the Executive's death.

         (l) "Subsidiary" means an entity, at least a majority of the total
voting power of the then-outstanding voting securities of which is held,
directly or indirectly, by the Company and/or one or more other Subsidiaries or,
for any entity that is not a corporation, at least a majority of the then-
outstanding capital interests of which is so held.

         (m) "Term" means (A) the period commencing on the date hereof and
ending on the second anniversary of the date hereof; provided, however, that
commencing on the date one year after the date hereof, and on each annual
anniversary of such date (such date and each annual anniversary thereof shall be
hereinafter referred to

                                       4
<PAGE>
 
as the "Renewal Date"), unless previously terminated, the Term shall be
automatically extended so as to terminate two years from such Renewal Date,
unless at least sixty (60) days prior to the Renewal Date the Company shall give
notice to the Executive that the Term shall not be so extended, (B) if, prior to
a Change of Control, for any reason the Executive is Terminated or Terminates,
thereupon without further action the Term shall be deemed to have expired and
this Agreement will immediately terminate and be of no further effect, and (C)
in the event of a Change of Control, the Term will, without further action, be
considered to terminate at the expiration of the Severance Period.

         (n) "Terminate" and correlative terms mean the termination of the
Executive's employment with the Company and any Affiliate or Subsidiary.

         (o) "Warburg" means Warburg, Pincus Capital Partners, L.P., and/or any
of its affiliates.

     2.  Termination Following a Change of Control:  (a) If, during the
         -----------------------------------------                      
Severance Period, the Executive is Terminated, the Executive will be entitled to
the benefits provided by Sections 3 and 4 unless such termination is by reason
of one or more of the following events:

               (i)   The Executive's death;

               (ii)  The permanent and total disability of the Executive as
defined in any long term disability plan of the Company, applicable to the
Executive, as in effect immediately prior to the Change of Control;

               (iii) Cause; or

               (iv)  The Executive's voluntary Termination in circumstances in
which Good Reason does not exist.

         (b) In the event of the occurrence of a Change of Control, the
Executive may Terminate during the Severance Period with the right to severance
compensation as provided in Sections 3 and 4 upon the occurrence of one or more
of the following events (regardless of whether any other reason, other than
Cause as hereinabove provided, for Termination exists or has occurred, including
without limitation other employment):

               (i)   An adverse change in the nature or scope of the
authorities, powers, functions, responsibilities, or duties attached to the
position with the Company; which the Executive held immediately prior to the
Change of Control;

               (ii)  A reduction in the Executive's Base Pay as in effect
immediately prior to any Change of Control, or as it may have been increased
from time to time thereafter;

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<PAGE>
 
               (iii) Any failure by the Company to continue in effect any plan
or arrangement providing Incentive Pay in which the Executive is participating
at the time of a Change of Control (or any other plans or arrangements providing
substantially similar benefits) or the taking of any action by the Company, any
Affiliate or Subsidiary which would adversely affect the Executive's
participation in any such plan or arrangement or reduce the Executive's benefits
under any such plan or arrangement in a manner inconsistent with the practices
of the Company prior to the Change of Control;

               (iv)  Any failure by the Company to continue in effect any
Employee Benefits in which the Executive is participating at the time of a
Change of Control (or any other plans or arrangements providing the Executive
with substantially similar benefits) or the taking of any action by the Company,
an Affiliate or Subsidiary which would adversely affect the Executive's
participation in or materially reduce the Executive's benefits under any
Employee Benefits or deprive the Executive of any material fringe benefit
enjoyed by the Executive at the time of a Change of Control;

               (v)   The liquidation, dissolution, merger, consolidation, or
reorganization of the Company or transfer of all or substantially all of its
business and/or assets, unless the successor or successors (by liquidation,
merger, consolidation, reorganization, transfer, or otherwise) to which all or a
significant portion of its business and/or assets have been transferred
(directly or by operation of law) assumed all duties and obligations of the
Company under this Agreement pursuant to Section 9;

               (vi)  Without limiting the generality or effect of the foregoing,
any material breach of this Agreement by the Company or any successor thereto;
or

               (vii) Any action by the Company which causes the Executive's
services to be performed at a location which is more than thirty five (35) miles
from the location where the Executive was employed immediately preceding the
date of the Change of Control.

         (c) Any Termination will be communicated by Notice of Termination
hereto given in accordance with Section 10 of this Agreement.

     3.  Severance Compensation:  (a)  If, following the occurrence of a Change
         ----------------------                                                 
of Control, the Executive is Terminated by the Company during the Severance
Period other than in the circumstances set forth in Section 2 (a) (i), 2 (a)
(ii), or 2 (a) (iii), or if the Executive Terminates for Good Reason:

               (i)   The Company will pay to the Executive in a lump sum in cash
within five (5) business days after the later of the date on which the Company
receives the determination of the Accounting Firm required in Section 4 hereof
or the Date of Termination the aggregate of the amount (the "Severance Payment")
equal to one and one-half times the sum of (A) the Executive's Base Pay at the
highest rate in effect at any time within the 90-day period preceding the date
the Notice of Termination was given or,

                                       6
<PAGE>
 
if higher, at the highest rate in effect at any time within the 90-day period
preceding the date of the first occurrence of a Change of Control, and (B) an
amount equal to the greatest amount of Incentive Pay received by the Executive
during any calendar year or portion thereof from and including the third
calendar year prior to the first occurrence of a Change of Control; and

               (ii)  For the period of one and one-half years from the Date of
Termination, the Executive shall be eligible for participation in and shall
receive all benefits under such benefit plans, practices, policies and programs
of the Company that provide medical, prescription dental, or life insurance
coverage, with the costs of such participation to be paid by the Company to the
same extent as prior to the Executive's Termination.  In the event that such
continued participation is not allowed under the terms and provisions of such
plans or programs, then in lieu thereof, the Company shall acquire individual
insurance policies providing comparable coverage for the Executive; provided
that if any such individual coverage is unavailable, the Company shall pay to
the Executive an amount equal to the contributions that would have been made by
the Company for such coverage on the Executive's behalf if the Executive had
remained in the employ of the Company for the period referred to in the
preceding sentence.

         (b) There will be no right of set-off or counter-claim in respect of
any claim, debt, or obligation against any payment to or benefit for the
Executive provided for in this Agreement.

         (c) Without limiting the rights of the Executive at law or in equity,
if the Company fails to make any payment or provide any benefit required to be
made or provided under this Agreement (including under this Section 3 or Section
6) on a timely basis, the Company will pay interest on the amount or value
thereof at an annualized rate of interest equal to the so-called composite
"prime rate" as quoted from time to time during the relevant period in the
Northeast Edition of The Wall Street Journal. Such interest will be payable as
                     -----------------------
it accrues on demand. Any change in such prime rate will be effective on and as
of the date of such change.

         (d) Notwithstanding any other provision hereof, the parties, respective
rights and obligations under this Section 3 and under Sections 4 and 6 will
survive any termination or expiration of this Agreement following a Change of
Control or any Termination following a Change of Control for any reason
whatsoever.

     4.  Excise and Other Taxes.  The Executive shall bear all expense of, and
         ----------------------                                                
be solely responsible for, all federal, state, local or foreign taxes due with
respect to any payment received hereunder, including, without limitation, any
excise tax imposed by Section 4999 of the Internal Revenue Code of 1986, as
amended (the Code); provided, however, that all payments under this Agreement
shall be reduced to the extent necessary so that no portion thereof shall be
subject to the excise tax imposed by Section 4999 of the Code but only if, by
reason of such reduction, the net after-tax benefit received by the Executive
shall exceed the net after-tax benefit received by the Executive if no such

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<PAGE>
 
reduction was made.  For purposes of this Section 4, "net after-tax benefit"
shall mean (i) the total of all payments and the value of all benefits which the
Executive receives or is then entitled to receive from the Company that would
constitute "parachute payments" within the meaning of Section 280G of the Code,
less (ii) the amount of all federal, state and local income taxes payable with
respect to the foregoing calculated at the maximum marginal income tax rate for
each year in which the foregoing shall be paid to the Executive (based on the
rate in effect for such year as set forth in the Code as in effect at the time
of the first payment of the foregoing), less (iii) the amount of excise taxes
imposed with respect to the payments and benefits described in (i) above by
Section 4999 of the Code.  The foregoing determination will be made by a
nationally recognized accounting firm (the "Accounting Firm") selected by the
Executive and reasonably acceptable to the Company (which may be, but will not
be required to be, the Company's independent auditors).  The Executive will
direct the Accounting Firm to submit its determination and detailed supporting
calculations to both the Company and the Executive within fifteen (15) days
after the Date of Termination.  If the Accounting Firm determines that such
reduction is required by this Section 4, the Company shall pay such reduced
amount to the Executive in accordance with Section 3 (a).  If the Accounting
Firm determines that no reduction is necessary under this Section 4, it will, at
the same time as it makes such determination, furnish the Company and the
Executive an opinion that the Executive will not be liable for any excise tax
under Section 4999 of the Code.  The Company and the Executive will each provide
the Accounting Firm access to and copies of any books, records, and documents in
the possession of the Company or the Executive, as the case may be, reasonably
requested by the Accounting Firm, and otherwise cooperate with the Accounting
Firm in connection with the preparation and issuance of the determinations and
calculations contemplated by this Section 4.  The fees and expenses of the
Accounting Firm for its services in connection with the determinations and
calculations contemplated by this Section 4 will be borne by the Company.

     5.  No Mitigation Obligation:  The Company hereby acknowledges that it
         ------------------------                                           
will be difficult, and may be impossible, for the Executive to find reasonably
comparable employment following the Date of Termination.  The payment of the
severance compensation by the Company to the Executive in accordance with the
terms of this Agreement will be liquidated damages, and the Executive will not
be required to mitigate the amount of any payment provided for in this Agreement
by seeking other employment or otherwise, nor will any profits, income,
earnings, or other benefits from any source whatsoever create any mitigation,
offset, reduction, or any other obligation on the part of the Executive
hereunder or otherwise.

     6.  Legal Fees and Expenses:  If the Company has failed to comply with any
         -----------------------                                                
of its obligations under this Agreement or in the event that the Company or any
other person takes or threatens to take any action to declare this Agreement
void or unenforceable, or institutes any litigation or other action or
proceeding designed to deny, or to recover from, the Executive the benefits
provided or intended to be provided to the Executive hereunder, the Company
irrevocably authorizes the Executive from time to

                                       8
<PAGE>
 
time to retain counsel of the Executive's choice, at the expense of the Company,
to advise and represent the Executive in connection with any such
interpretation, enforcement, or defense, including without limitation the
initiation or defense of any litigation or other legal action, whether by or
against the Company or any member of the Board, officer, stockholder, or other
person or entity affiliated with the Company, in any jurisdiction. The Company
will pay and be solely financially responsible for any and all attorneys' and
related fees and expenses incurred by the Executive in connection with such
litigation.

     7.  Employment Rights:  Nothing expressed or implied in this Agreement
         -----------------                                                  
will create any right or duty on the part of the Company or the Executive to
have the Executive remain in the employment of the Company, or any Affiliate or
Subsidiary prior to or following any Change of Control.

     8.  Withholding of Taxes:  The Company may withhold from any amounts
         --------------------                                               
payable under this Agreement all federal, state, city, or other taxes as the
Company is required to withhold pursuant to any law or government regulation or
ruling.

     9.  Successors and Binding Agreement:  (a)  The Company will require any
         --------------------------------                                     
successor (whether direct or indirect, by purchase, merger, consolidation,
reorganization, or otherwise) to all or substantially all of the business and/or
assets of the Company, by agreement in form and substance satisfactory to the
Executive, expressly to assume and agree to perform this agreement in the same
manner and to the same extent the Company would be required to perform if no
such succession had taken place.  This Agreement will be binding upon and inure
to the benefit of the Company and any successor to the Company, including,
without limitation, any persons acquiring directly or indirectly all or
substantially all of the business and/or assets of the Company, whether by
purchase, merger, consolidation, reorganization, or otherwise (and such
successor will thereafter be deemed the "Company" for the purposes of this
Agreement), but will not otherwise be assignable, transferable, or delegable by
the Company.

         (b) This Agreement will inure to the benefit of and be enforceable by
the Executive's personal or legal representatives, executors, administrators,
successors, heirs, distributees, and/or legatees.

         (c) This Agreement is personal in nature and neither of the parties
hereto will, without the consent of the other, assign, transfer, or delegate
this Agreement or any rights or obligations hereunder except as expressly
provided in Sections 9 (a) and 9 (b).  Without limiting the generality or effect
of the foregoing, the Executive's right to receive payments hereunder will not
be assignable, transferable, or delegable, whether by pledge, creation of a
security interest, or otherwise, other than by a transfer by will or by the laws
of descent and distribution and, in the event of any attempted assignment or
transfer contrary to this Section 9 (c), the Company will have no liability to
pay any amount so attempted to be assigned, transferred, or delegated.

                                       9
<PAGE>
 
     10. Notices:  For all purposes of this Agreement, all communications,
         -------                                                           
including, without limitation, notices, consents, requests, or approvals,
required or permitted to be given hereunder will be in writing and will be
deemed to have been duly given when hand delivered or dispatched by electronic
facsimile transmission (with receipt thereof orally confirmed), or two business
days after having been mailed by United States registered or certified mail,
return receipt requested, postage prepaid, or one business day after having been
sent by a nationally recognized overnight courier service addressed to the
Company (to the attention of the General Counsel of the Company) at its
principal Executive office and to the Executive at the Executive's principal
residence, or to such other address as any party may have furnished to the other
in writing and in accordance herewith, except that notices of changes of address
will be effective only upon receipt.

     11. Governing Law:  The validity, interpretation, construction, and
         -------------                                                   
performance of this Agreement will be governed by and construed in accordance
with the substantive laws of the State of Connecticut, without giving effect to
the principles of conflict of laws of such State, to the extent not preempted by
applicable federal law.

     12. Validity:  If any provision of this Agreement or the application of
         --------                                                            
any provision hereof to any person or circumstances is held invalid,
unenforceable, or otherwise illegal, the remainder of this Agreement and the
application of such provision to any other person or circumstances will not be
affected, and the provision so held to be invalid, unenforceable, or otherwise
illegal will be reformed to the extent (and only to the extent) necessary to
make it enforceable, valid, or legal.

     13. Non-Exclusivity of Rights:  Nothing in this Agreement will prevent or
         -------------------------                                             
limit the Executive's present or future participation in any benefit, bonus,
incentive, or other plan or program provided by the Company or any Affiliate or
Subsidiary for which the Executive may qualify, nor will this Agreement in any
manner limit or otherwise affect such rights as the Executive may have under any
stock option or other agreements with the Company or any Affiliate or
Subsidiary. Amounts or benefits which are vested or which the Executive is
otherwise entitled to receive under any plan or program of the Company at or
subsequent to the Date of Termination will be payable in accordance with such
plan or program, except as otherwise expressly provided in this Agreement;
provided, however, that any amounts received by the Executive pursuant to this
Agreement shall be in lieu of any benefits which the Executive is entitled to
receive or may become entitled to receive under any reduction-in-force or
severance pay plan or practice which the Company now has in effect or may
hereafter put into effect, any other benefits to which the Executive may be
entitled under any individual agreement of employment with the Company which
would provide a benefit to the Executive upon the occurrence of a Change of
Control of the Company, and any severance benefits required under federal or
state law to be paid to the Executive.

     14. Miscellaneous:  (a)  No provision of this Agreement may be modified,
         -------------                                                        
waived, or discharged unless such waiver, modification, or discharge is agreed
to in 

                                       10
<PAGE>
 
writing signed by the Executive and the Company. No waiver by either party
hereto at any time of any breach by the other party hereto or compliance with
any condition or provision of this Agreement to be performed by such other party
will be deemed a waiver of similar or dissimilar provisions or conditions at the
same or at any prior or subsequent time. No agreements or representations, oral
or otherwise, express or implied with respect to the subject matter hereof have
been made by either party which are not set forth expressly in this Agreement.
References to Sections are to references to Sections of this Agreement.

         (b) The Executive and the Company acknowledge that this Agreement
supersedes any other agreement between them concerning the subject matter
hereof.


         IN WITNESS WHEREOF, the parties have caused this Agreement to be duly
executed and delivered as of the date first above written.

                                        ADVO, Inc.


                                        By  ROBERT KAMERSCHEN /s/
                                           ----------------------
                                           Robert Kamerschen



                                           A. BRIAN SANDERS /s/
                                           ----------------------     
                                           A. Brian Sanders

                                       11