"Balsa is a GNOME email client. It supports mbox, maildir,
and mh local mailboxes, and IMAP4 and POP3 remote mailboxes. You
can send mail via sendmail or SMTP. Optional multithreading
support allows for non-instrusive retrieval and sending of mail. A
finished GUI similar to that of Eudora lets you view images inline,
save message parts, view headers, add attachments, move messages,
print messages, and just about anything you would expect in a
robust mail client."