Zimbra praised by ZDNET article: Top alternatives to Microsoft Outlook
Top alternatives to Microsoft Outlook - page 13 : Insight - Software - Page 13 - ZDNet Australia
Notable quote: Zimbra is perhaps the most affordable product which has both vendor support and multiple OS compatibility — not to mention a feature set comparable to market leaders like Microsoft, Novell and IBM/Lotus. A free version of Zimbra is also available and it is suggested that businesses investigate the trial version first.
Thought it worth sharing :)