quirrelMail is a project that provides both a web-based email client
and a proxy server for the IMAP protocol. SquirrelMail webmail
is available for any platform supporting PHP. The SquirrelMail
webmail client itself is a complete webmail system, but extra
features are available in the form of plugins. There are over 200
third-party plugins available for download from the SquirrelMail
website and SquirrelMail ships with several "standard" or "core"
plugins. SquirrelMail webmail has been translated into over 50
languages.