IMP (Internet Messaging Program) provides a rich web-based messaging environment that can be accessed over the Internet. IMP can act as a frontend to many different kinds of mail servers working on POP3, POP3S, IMAP or IMAPS. It works seamlessly with all RFC-compliant POP/IMAP servers (e.g. Dovecot, Cyrus, Courier, MS Exchange).

Features

A List of IMP's Features (as of IMP 4.0)

Screenshots

http://www.horde.org/imp/screenshots/
http://janschneider.de/horde/ansel/view.php?gallery=71