Résumé : added the australian emacs users list
< ; mailto:firstname.lastname@example.org: The spanish Emacs users mailing list [http://es.gnu.org/cgi-bin/mailman/listinfo/emacs-es Subscribe or Archive]
> ; mailto:email@example.com: The Spanish Emacs users mailing list [http://es.gnu.org/cgi-bin/mailman/listinfo/emacs-es Subscribe or Archive]
> ; mailto:firstname.lastname@example.org: The Australian Emacs users mailing list [http://lists.softwarefreedom.com.au/cgi-bin/mailman/listinfo/emacs-au-discuss Subscribe or Archive]
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.
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.