"Since I started using email in 1995, I've been on a (seemingly)
never-ending quest for the perfect email client. I've used
text-based, Web-based, and GUI email clients, on Linux, Windows,
and Mac OS, and have yet to find one mail user agent (MUA) that I'd
consider 'perfect.' There are some really, really good MUAs--such
as Mutt and Mozilla Thunderbird--but I haven't found the perfect
mailer just yet. Sylpheed 2.0, however, is getting close.
"Sylpheed is a light-weight MUA that uses the GIMP Toolkit
(GTK+), and offers excellent mail filtering features, junk mail
control and--in fine *nix fashion--cooperation with external
commands. Sylpheed is licensed under the GNU General Public License
(GPL) and runs on Unix-type OSes, such as Linux, BSD, and Mac OS X.
A Windows port is in progress..."