XCmail is a MIME- and POP3-capable e-mail client for X11.  It has
plugins to display various kinds of MIME attachments.  There is an
address book.  XCmail can work with a local mailbox--or several--and
POP3.  With POP3, it can use the UIDL function and cache the UIDL
history so mail which is left on the POP server but deleted on the
client is only downloaded once.  XCmail has RFC 2015-compliant
support for encrypted mail in multipart MIME format.

WWW:  http://www.js-home.org/XCmail/

Trevor Johnson