EXHIBIT 99.1

                  CMGI STRENGTHENS INTERNET MARKETING ARSENAL WITH
                               ACQUISITION OF ADFORCE

         Acquisition Solidifies Interactive Ad Serving, Measurement, Sales
                       and Targeting Infrastructure for CMGI

Andover, Mass. and Cupertino, CA, September 20, 1999 - CMGI, Inc. (Nasdaq:
CMGI) announced today that it has signed a definitive agreement to acquire
AdForce, Inc. (Nasdaq: ADFC) in a stock-for-stock tax-free merger valued at
approximately $500 million. Under the terms of the agreement, CMGI will issue
0.262 CMGI shares for every share of AdForce held on the closing date of the
transaction. Closing of the merger is subject to customary conditions,
including formal approval by AdForce shareholders, expected later this year.

The merger builds on both companies' strengths to create a broad
infrastructure for the overall delivery of ad serving and digital media
services, and is yet another addition to CMGI's strong stable of core
advertising infrastructure technologies. Following completion of the
acquisition, AdForce will become the latest member of CMGI's group of
majority-owned operating companies.

According to David Andonian, President of Corporate Development for CMGI,
"AdForce has significantly increased their reach and momentum over the last
year to become a leader in the delivery and measurement of online advertising
campaigns. As a part of the CMGI network, AdForce will continue to expand its
customer base by providing services to many of the CMGI-affiliated companies,
well beyond their current Adsmart and Engage relationships. The integration
of AdForce's highly scalable ad serving and measurement tools is another
important step in helping CMGI reach its goals of building a
fully-integrated, interactive marketing machine."

Chuck Berger, AdForce Chairman and CEO added, "The rapid growth in the demand
of online advertising services will continue to accelerate, reaching a
projected market size of more than $32 billion by the year 2004, according to
Forrester Research. To creation, delivery and analysis of their marketing
campaigns. The combination of AdForce's state of the art ad delivery and
CMGI's leading content and infrastructure companies will create a new kind of
digital marketing company, capable of providing the full range of services
required by the global Internet economy".

This agreement furthers the relationship established between AdForce and CMGI
earlier this year as a result of AdForce's strategic partnerships with Engage
and Adsmart, two of the CMGI operating companies. As previously announced,
AdForce is currently the primary ad-serving company for the Adsmart Network
(http://www.adsmart.net), now including more than 300 Web sites totaling 2
billion monthly impressions. In addition, Engage and AdForce announced a
collaborative solution that combines AdForce's centralized online ad
management system with Engage's Precision Profiling technology and consumer
interest data from Engage Knowledge, a Web wide database containing more than
30 million anonymous consumer interest profiles. Engage enablement of the
AdForce ad management system is on target for completion in Q4 1999.

As a formal member of the CMGI network, AdForce can strengthen these
relationships while making its technology more broadly available to the
nearly 50 CMGI affiliated companies.

About AdForce
AdForce is "The Force in .com Marketing"-SM- and a leading provider of
centralized advertising services, enabling online publishers, rep firms and
advertisers to leverage the unique advantages of the Internet as the first
fully interactive medium. Deploying advanced scalable technology and backed
by robust data centers, the AdForce service delivers billions of impressions
monthly for some of the Internet's most prominent advertisers. AdForce
provides a comprehensive suite of products, which allow advertisers, and
publishers to target, deliver, measure and analyze Internet advertising
programs for the best results. AdForce has strategic partnerships with
America Online Inc., Engage Technologies, Sina.com, and Experian (formerly
Metromail). AdForce has offices in Cupertino, CA, Costa Mesa, CA, and New
York, NY.

About CMGI
With nearly 50 companies, CMGI, Inc. (Nasdaq: CMGI) represents the largest, most
diverse network of Internet



companies in the world. This network includes both CMGI operating companies
and a growing number of synergistic investments through its venture capital
affiliate, @Ventures. CMGI leverages the technologies, content, and market
reach of its extended family of companies to foster rapid growth and industry
leadership across its network, and the larger Internet Economy. Microsoft,
Intel, Sumitomo and Compaq hold minority positions in CMGI.

CMGI's majority-owned subsidiaries include Engage Technologies (Nasdaq:
ENGA), Activerse, Adsmart, AltaVista, Cha! Technologies, iCAST, Magnitude
Network, NaviSite, NaviNet, Planet Direct and ZineZone. The company's
@Ventures affiliates have ownership interests in Lycos, Inc. (Nasdaq: LCOS),
Critical Path (Nasdaq: CPTH), Silknet (Nasdaq: SILK), Chemdex (Nasdaq: CMDX),
Advoco.com, Ancestry.com, Asimba, AuctionWatch, Aureate Media, blaxxun,
BizBuyer.com, buyingedge.com, CarParts.com, eCircles.com, Furniture.com,
HotLinks, Intelligent/Digital, KOZ.com, Mondera.com, MotherNature.com,
NextMonet.com, NextPlanetOver.com, OneCore.com, ONElist, PlanetOutdoors.com,
Productopia, Promedix.com, Raging Bull, Softway Systems, Speech Machines,
ThingWorld.com, Vicinity, Virtual Ink, Visto and WebCT.

CMGI is also the majority-owner of SalesLink, InSolutions and On-Demand
Solutions, leaders in the direct marketing, fulfillment and turnkey arenas.
CMGI Corporate headquarters is located at 100 Brickstone Square, Andover, MA
01810. Telephone: 978-684-3600. Fax: 978-684-3814. Additional information is
available on the company's Web site at http://www.cmgi.com.

This press release contains certain forward-looking statements within the
meaning of Section 27A of the Securities Act of 1933, as amended, and Section
21E of the Securities Act of 1934, as amended. These statements, including
without limitation statements regarding the expected growth in the market for
online advertising services, are subject to the "safe harbor" created by
those sections and include, but are not limited to the anticipated results of
the merger. AdForce's actual results for future periods could differ
materially from those predicted in these forward-looking statements. Factors
that could cause actual events or results to differ include, but are not
limited to its ability to maintain the performance and reliability of its
systems, its need to continue scaling its systems successfully and to add new
features and functionality to meet market demands, contractual provisions
permitting termination of agreements between AdForce and its customers,
competitive pressures affecting AdForce and/or its customers, AdForce's
ability to integrate its services with those of CMGI companies, and other
risks described in AdForce's Registration Statement on Form S-1, as amended,
and Quarterly Report on Form 10-Q filed with the Securities and Exchange
Commission. AdForce undertakes no obligation to update forward-looking
statements to reflect events or circumstances occurring after the date of
such statements.  "Safe Harbor" Statement under the Private Securities
Litigation Reform Act of 1995: Statements in this press release regarding
CMGI, Inc.'s business, including without limitation statements regarding the
expected growth in the market for online advertising services, which are not
historical facts are "forward-looking statements" that involve risks and
uncertainties. For a discussion of such risks and uncertainties, which could
cause actual results to differ from those contained in the forward-looking
statements, see "Risk Factors" in the CMGI Annual Report or Form 10-K for the
most recently ended fiscal year.

                                       # # #

Company Contact:                        Company Contact:
Dee Cravens                             Deidre Moore
Vice President, Marketing               Director of Public Relations
AdForce, Inc.                           CMGI, Inc.
Voice: 408.873.3680 x143                Voice: 978-684-3655
E-mail: dcravens@adforce.com            E-mail: dmoore@cmgi.com
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