The new Google Groups, which has been available as a Google Labs test since May, brings the search giant the type of community feature that has been a fixture for such competitors as Yahoo Inc. and Microsoft Corp.s MSN division.
For its e-mail list service, Google is emphasizing its combination of user-formed groups with Usenet and its search functionality.
Not only can users search for e-mail postings within Google Groups, but they also can retrieve group postings as part of Web searches. Google Groups messages are added to Googles Web index within minutes of being posted, if a group is publicly available, said Marissa Mayer, Googles director of consumer Web products.
For Google, the e-mail lists provide an important source of Web content for searchers, such as personal reviews on products and hints on solving technical problems, Mayer said.
"One thing we noticed over time is that content comes up in discussion groups that doesnt come up anywhere else," Mayer said
Google acquired its Usenet archive from Deja.com in 2001. Since then, it made the archive available and searchable through Google Groups, but until the test of Google Groups 2 it did not allow for the creation of new lists.
Usenet includes more than 1 billion posts, according to Google.
During the Labs beta, users created thousands of new e-mail groups, Mayer said. She declined to provide exact numbers.
Google Groups users can create public or private e-mail lists and restrict membership. Those subscribed to groups can receive messages by e-mail or view the ongoing conversations from a URL created for each group.
Google Groups also provides another outlet for Googles advertising programs, which account for the bulk of its revenues.
Google Groups includes both its AdWords sponsored links, which appear based on a users search, and its AdSense contextual ads, which appear based on the content of an e-mail group, Mayer said.
The new Google Groups initially is available in English only, but Google is planning to create versions for other languages in coming months.