Offer your customers secure, business-level email hosting with various value added services. An excellent solution for SPs, suitable for hundreds to millions of users.
An innovative messaging solution [...] offering important premium features.- The Radicati Group -
Axigen looks like a good, easy-to-use option if you want a full-featured email server.- ServerWatch-
A professional e-mail server with Web interfaces for both administration and user mail.- Linux Journal-