Mutt is a small but very powerful MIME mail client for Unix-like operating
systems, similar to PINE, ELM and MUSH.  It is highly configurable
(including key bindings), allows sorting by threads, and has support for
color terms (using ncurses or S-Lang).

Mutt's home page is http://www.mutt.org/
The primary ftp site is ftp.mutt.org/pub/mutt/.
A list of mirror ftp sites can be found at 
http://www.mutt.org/download.html.