What about Zimbra ?
I am surprised not to see Zimbra shown in the results especially when they have recently hit 40+ million paid mailboxes ? http://www.zimbrablog.com/blog/archives/2009/03/zimbra-turns-40%E2%80%A6-million-that-is.html
Messaging is a thread that runs through IT from top to bottom, from humans exchanging information with each other, down to software and even hardware exchanging status messages and information packets. This report, which is based on feedback from readers of The Register provided during our last annual Barometer Survey, …