Roundcube - Web-based IMAP email client
Cdw - cdw: ncurses interface for GNU/Linux command line CD/DVD tools
Mailo - Mailo is an email client where you can send and receive emails to and from anyone with an email address.
CompuCom - Technology Solutions for the Digital Workplace
HEY - Email at its best, new from Basecamp.
Sirius - An open-source clone of Siri from UMICH