Main Page | See live article | Alphabetical index A Mail server is a computer server which provides SMTP, POP3 and/or IMAP services. This enables the sending and receiving of email messages. There are several programs that run on mail servers: Table of contents 1 SMTP 2 POP/IMAP 3 Mail filtering SMTP Sendmail - The most versatile, but the one with the most cryptic configuration file. It has had a history of security holes, including the Morris worm. Postfix - By Wietse venema. This MTA is designed for security, with several separate programs each of which does a task. qmail - By Dan Bernstein. Similar in design to Postfix. Additionally the programs run as different user IDs. Exim Courier POP/IMAP UW IMAP - Uses mbox format. Courier IMAP - Uses Maildir format, which is much faster and requires no file locking. Mail filtering Procmail - A general-purpose mail-sorting program. Vipul's Razor - By Vipul Ved Prakash. Razor users (which may be spamtraps) report spam to Razor; mail servers ask Razor whether incoming messages are spam. SpamAssassin - Uses several criteria, including Razor, to recognize spam. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.