SurgeMail is a fully featured enterprise class mail server with integrated web based email, web based account and server administration. You can even configure it out of the box to automate user sign up (great for running free/low cost public mail services like hotmail)
The web based email system builds on NetWin's well known SurgeWeb WebMail system with extensive customization options using templates. Combine this with SurgeMail's inbuilt web server and you have an all in one solution that does not require extensive work to get components working together.
SurgeMail has many features for high reliability systems such as in-built server mirroring and support for clustered and proxy configurations, NFS based mail storage etc.