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                                                                   EXHIBIT 10.20

                             AMENDMENT #5 TO LEASE
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1.  Parties.
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    This Amendment, dated as of December 18,  2000, is between Andover Mills
Realty Limited Partnership ("Landlord") and CMGI, Inc. ("Tenant").

2.  Recitals.
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    2.1  Landlord and Tenant have entered into Lease, dated as of April 12,
1999, for space in Brickstone Square in Andover, Massachusetts (as now or
hereafter amended, the "Lease").  Unless otherwise defined, terms used in this
Amendment have the same meanings as those used in the Lease.

    2.2  Tenant no longer wishes to lease the following portions of the
Premises in Building 200 (collectively, the "Terminated Space"), totaling 92,700
s.f. of agreed rentable area: Offer Space #1 (2/nd/ Floor, 29,916 s.f.); Fifth
Expansion Space #1 (3/rd/ Floor, 14,198 s.f.); Fifth Expansion Space #2 (3/rd/
Floor, 15,695 s.f.); and the Temporary Space (5/th/ Floor, 32,891 s.f.).
Accordingly, Landlord and Tenant have agreed that Tenant will assign and
transfer its interest in the Terminated Space to Landlord and that the Lease
will then terminate with respect to the Terminated Space only.  In order to
accomplish this and other matters, for good and valuable consideration, the
receipt and sufficiency of which is acknowledged, the parties agree and the
Lease is amended as follows as of the date hereof, notwithstanding anything to
the contrary:

3.  Amendments.
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    3.1  As of the date hereof, Tenant assigns, conveys and transfers to
Landlord all of Tenant's right, title and interest in and to the Terminated
Space, and: (a) the Lease will terminate and expire as to the Terminated Space
only and Tenant and its Affiliates will vacate and surrender possession of the
Terminated Space; (b) the agreed rentable area of the remainder of the Premises
will be 321,189; and (c) Tenant's parking rights under the Lease will be reduced
by two hundred seventy-eight (278) vehicles, Exhibit "A-4" attached to Amendment
#3 to Lease will be deemed deleted from the Lease and Exhibit "A-5" attached
hereto and incorporated herein (which shows a new parking plan for Tenant) will
be substituted in its place.  Despite the earlier termination of the Lease with
respect to the Terminated Space, and in addition to other rent payable under the
Lease, all rent that would have been payable by Tenant in connection with each
portion of the Terminated Space absent this termination will continue to be paid
as rent under the Lease through the first to occur of: April 30, 2001, or the
date that a new tenant under a new lease of that portion of the Terminated Space
occupies that portion of the Terminated Space to conduct business, or the rent
commencement date under any new lease of that portion of the Terminated Space.
(As a hypothetical example, if Offer Space #1, 29,916 s.f., is leased by
Landlord pursuant to a new lease with a rent commencement date of February 1,
2001, rent payable by Tenant for Offer Space #1 would be payable only through
January 31, 2001.)  In Section 27(e)(i) of the Lease, the figure "500,000 square
feet" will be deemed reduced to "407,300 square feet".  Following the effective
termination date of the Lease with respect to the Terminated Space, neither
party will have any further rights or obligations to the other with respect
thereto (except for any unpaid rent due under

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the Lease or hereunder for any period before the termination date with respect
to the Terminated Space).

     3.2  As of the effective termination date of the Lease with respect to the
applicable portion of the Terminated Space, Tenant's Percentage will be deemed
decreased as follows: Offer Space #1 - 3.18%; Fifth Expansion Space #1 - 1.51%;
Fifth Expansion Space #2 - 1.67%; and the Temporary Space - 3.50%.  Following
the effective  termination date of the Lease with respect to all of the
Terminated Space, Tenant's Percentage will be 34.15%, assuming that Tenant
leases no other space in the Project.

     3.3  As a material inducement to Landlord to enter into this Amendment,
Tenant agrees that, as of the date hereof, Landlord is not, to Tenant's
knowledge, in default under the Lease, and Tenant represents to Landlord that
Tenant has not subleased, assigned or conveyed the Terminated Space or its
interests therein to anyone else.

     3.4  As a material inducement to Tenant to enter into this Amendment,
Landlord agrees that, as of the date hereof, Tenant is not, to Landlord's
knowledge, in default under the Lease.

     Time is of the essence in this Amendment and holding over will not be
permitted.  Notwithstanding anything herein to the contrary, this Amendment will
not be binding on Landlord until and unless Landlord receives approval from its
current Landlord's Mortgagee.  Promptly after receiving such approval (or
disapproval, as the case may be) from its current Landlord's Mortgagee, Landlord
will notify Tenant of same in writing.  The Lease remains in full force and
effect, and except as set forth above, the Lease remains unchanged.

     IN WITNESS WHEREOF, intending to be legally bound, the parties have
executed this Amendment as of the date in Article 1 above.


CMGI, Inc., a Delaware corporation        Andover Mills Realty Limited
                                          Partnership, a Massachusetts limited
                                          partnership

By:  /s/ Andrew J. Hajducky, III          By:  Brickstone Square Realty, Inc., a
     Name:  Andrew J. Hajducky, III            Massachusetts corporation,
     Title: Chief Financial Officer            general partner
     Authorized Signature

                                               By:  /s/ Martin Spagat
                                                    Name:  Martin Spagat
                                                    Title: Vice President
                                                    Authorized Signature

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