Obviously a lot of mailing lists have been founded to discuss Emacsen. The official GnuEmacs lists are hosted at the GNU nurtury Savannah. See the Emacs project page there for a complete list. The primary XEmacs lists are hosted by http://xemacs.org, as listed on http://xemacs.org/Lists/index.html.

The various Emacs programs might have their own lists too. Check the homepages of these proggies, and if EmacsWiki has an entry. Many of them live on Savannah or SourceForge?. Don’t worry too much about posting to a generic list though, the ever-helpful people there will redirect you to a more specific list if they considered necessary.

A directory of the lists

Lists to seek help from

help-emacs-windows, mailto:help-emacs-windows@gnu.org
Emacs on Windows help
help-gnu-emacs, mailto:help-gnu-emacs@gnu.org
Emacs help (also one of the EmacsNewsgroups)

Lists for development

emacs-devel, mailto:emacs-devel@gnu.org
Emacs development Archive
xemacs-beta, mailto:xemacs-beta@xemacs.org
XEmacs development
xemacs-patches, mailto:xemacs-patches@xemacs.org
XEmacs patches
bug-gnu-emacs, mailto:bug-gnu-emacs@gnu.org
Emacs bugs and feature requests, use M-x report-emacs-bug on Emacs to send stuff to the list (also one of the EmacsNewsgroups)
emacs-pretest-bug, mailto:emacs-pretest-bug@gnu.org
Emacs bugs for a pretest release. As of 2008-08, merged with emacs-devel. Archive still exists.

National and regional lists

The Brazilian Emacs users mailing list Subscribe or Archive
The Spanish Emacs users mailing list Subscribe or Archive
The Australian Emacs users mailing list Subscribe or Archive

Other Lists

Emacs announcements. List information, Archive
gnu-emacs-sources, mailto:gnu-emacs-source@gnu.org
Emacs source code posts only. List information (also one of the EmacsNewsgroups).
debian-emacsen, mailto:debian-emacsen@lists.debian.org
Support and developer discussion on Emacs related packages for Debian GNU/Linux. List information
macosx-emacs, mailto:macosx-emacs@email.esm.psu.edu
Support for Emacs on Mac OS X, in particular AquamacsEmacs. List information, Archive

Mailing lists via news

Some of the EmacsNewsgroups are bidirectionally gatewayed as mailinglists, and vice versa. Generally it is better if you subscribe to newsgroups instead of mailing lists, because then the load is spread amongst many newsservers instead of one mailing list host.

Quite a lot of EmacsMailingLists are available as EmacsNewsgroups too, throught one gateway or an another. One such gateway is Gmane, where their hierarchy gmane.emacs contains most of the Emacs-related lists available there.