Whether the shuttering of the AOL service should be seen as a sign of a decline of the importance of mailing lists is a matter of debate. Though they don't attract the media attention of newer social networking services such as Twitter and Facebook, mailing lists can still be a hotbed of activity, as anyone who follows and the security-focused mailing list knows.

"The traditional email-only LISTSERV platform as we've known it has definitely declined in importance, supplanted in large measure through Web-based discussions and online group platforms," said Joe Loong of Reston, Virginia. Loong received the AOL notice, though he hadn't worked with any of the mailing lists he administered in more than four years.

Much of the discussions that used to take place on mailing lists have moved to Facebook or online groups hosted by Yahoo, Google and others. "I think ending it is just a recognition that there are plenty of other mechanisms and services available to host those kinds of discussions," Loong said. "List owners are probably pretty well cognitively locked into what they've currently got, but they do have a lot more options these days, many of them still free."

The AOL LISTSERV currently hosts about 640 mailing lists, ranging in topics from the cotton industry to the New York Mets. Some lists are still active; others aren't.

One list still somewhat active is the discussion list for AOLserver, AOL's open-source Web server software. The administrator for this list SourceForge, where the AOLserver code is housed. However, the administrator, Dossy Shiobara, noted that there was no immediate way to move the decadelong archives of this mailing list, along with related announcement lists, to SourceForge. Fortunately, much of the content is mirrored on other sites, however.