Mailutils is a swiss army knife of electronic mail handling.
It offers a rich set of utilities and daemons for processing
the e-mail.

All Mailutils programs are able to operate on mailboxes of 
any existing format, ranging from standard UNIX maildrops,
through maildir and up to remote mailboxes, which are
transparently accessed using IMAP4, POP3 and SMTP.

WWW: http://mailutils.org/