Eicq: ICQ client integrated into XEmacs.
Emacs Wiki Mode: A wiki-like publishing tool and personal information manager that allows to create a wiki on local system and can publish to HTML format.
Emacs-w3m: A simple Emacs interface to a text-mode WWW browser.
Emacs/W3: A web browser completely written in Elisp.
Etach: Emacs extension for MIME attachments and detachments works in RMAIL and Mail modes.
Gnus 5.x FAQ: Answers to frequently asked questions in hypertext.
Gnus Newsreader Homepage: An acronym for Gnus Network User Services, a news and mail reader with threading, ratings, self documentation.
Insidious Big Brother DB: An addressbook and contact management database for emacs mail and news clients.
Mailcrypt: An Emacs/PGP Interface: Encrypt/decrypt mail with PGP 5.0 or GnuPG.
Mew: An acronym of "Messaging in the Emacs World". Runs with Unix, Windows, OS/2, and supports folders, threads, mail aliases.
Mew and BBDB: Mailer together with database for contact and address management.
mh-e Information: From the O'Reilly book "MH and nmh."
MUTT with Emacs: Short guide for installation and use with emacsclient.
My.gnus.org: An attempt to complement the existing website by offering a single entry point for other Gnus resources, Gnus and Emacs links and the Gnus tutorial project.
Reading Lotus Notes Mail Using Emacs: Use Pop3 to access the mailbox.
Riece: An IRC client for Emacs featuring multiple panes.
Rmail: The default mail reader which ships with every emacs.
Sending Authenticated Mail (rfc2554): For smtp sessions with gnus.
Sending Mail: Gnu manual explaining the default configuration for sending mail in emacs.
Supercite User's Manual: Provides sophisticated facilities for the citing and attributing of message replies.
The Insidious Big Brother Database: The creator, JWZ, still maintains a page with interesting historical information.
The Mh-e Den: Official site of the front end to the MH mailer, at Sourceforge.
VM Homepage: The author, Kyle Jones, maintains the official page for this alternative to Gnus, Rmail, and the others.
Wanderlust: Uses IMAP to manage and read mail, strong Japanese support.