Usenet is also called network news, NNTP, or just news. It can be likened to a distributed bulletin board, where messages posted on one board (or server) are forwarded to other boards (or servers) in a network. There are many specialized newsgroups and news servers. An ISP will often provide a news server for its customers, and large corporations occasionally provide them for use by staff. Commercial Usenet providers are in operation, and an archive of Usenet posts is available at http://groups.google.com/.
The first spammers collected their email addresses from Usenet. Even today, it is the second greatest source of email addresses.
Most news servers do not require a user to provide an email address to read posts on newsgroups. However, most require a user to provide an email address when posting messages. If a user only reads newsgroups, their email address will not be collected by spammers from Usenet. Some mailing lists are also echoed to Usenet and subscribers to it are at risk...