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.