Mailing lists are a special usage of email that allows for widespread distribution of information to many Internet users. Software is installed on a computer which processes incoming email messages, and, depending on their content, either acts on them internally or distributes the message to all users subscribed to the mailing list. Popular examples of mailing list software include GNU Mailman and Majordomo. Today, mailing lists are most often used for collaboration on various projects and as a way of distributing current news and other such information. One very popular mailing list is Bugtraq.

Free web-based services offering an easy way to run and maintain such lists were popular in the late 1990s, but many of these were taken over or went bust, so that the only popular provider is now Yahoo! Groups. This is used by a wide range of groups, including organisations who might at first glance be considered 'rivals' to Yahoo! MSN Groups appears to be pushing hard to catch up to Yahoo! though.

See Wikipedia:Mailing lists for Wikipedia's mailing lists.

See also: mailing list archive, GMANE