post-mode is an emacs major mode. If you use emacs as your text editor with the mutt mail client then you should use post-mode to make your life easier.

Abook is a text-based addressbook program designed to use with mutt mail client. Abook runs on Linux, FreeBSD and some other UNIXes.

The Woodnotes Guide to the Mutt Email Client

Muttprint formats the output of mail clients to a good-looking printing. It uses the typesetting system LaTeX, which is normally part of every Linux distribution and which is also available for other operating systems like *BSD and Solaris.