Sylpheed - an X based e-mail client has features (or go for it :-))
o user-friendly and intuitive interface
o 3-paned view like many Windoze-based mail client
o ability of keyboard-only operation
o Mew/Wanderlust-like key bind
o multipart MIME
o unlimited multiple account handling
o message queueing
o assortment function
o XML-based address book
o APOP support
o unread message management
o MH folder support
o multithread support (experimental)
o can import mbox
o drag & drop (partially implemented)
o fast thread display
o high-speed message processing
o lightweight resource usage
o easily customizable configuration
o "Attract by subject" faculty, which is convenient when thread is
  broken on Mailing List and so on.
o supports automake + autoconf, and internationalization of message by gettext
o integrated NetNews client (partially implemented)