Mailing Lists:
mutt-users, mutt-dev
http://www.mutt.org/mail-lists.html
For users or developers, pick one.
 

 

 
User Groups:

 

 
Discussion Boards:
The Mutt Wiki
http://wiki.mutt.org/
 

 

 
Chat Rooms:
#mutt on irc.freenode.net
IRC