A web based webmail system

 IMP, the Internet Mail Program, is one of the most popular and widely deployed
 open source webmail applications in the world. It allows universal, web-based
 access to IMAP and POP3 mail servers and provides Ajax, mobile and traditional
 interfaces with a rich range of features normally found only in desktop email
 clients.
 .
 This package is part of Horde, a web application Framework written in PHP with
 modules like IMP (webmail), Turba (contacts), Kronolith (calendar), Nag (task
 list), Gollem (file manager), etc.