GPLW3Mail is a webmail application written in Perl. It is only designed to work with POP3 mailboxes (for IMAP-based mail there exist other applications). It is a splinter project based upon W3Mail.
Six evil magi flee from their home world, and now cpreading chaos and horror across the galaxy. Only the Magi Slayer can stop them and bring back harmony and order.
fruMailer is a cross platform MUA written in both Java and Perl. The GUI is based off of the toolbar-and-windows idea behind the GIMP.
Mailtide is an ajax based webmailer. It is possible to manage several mailaccounts under one user interface. Also a calendar will be included.