Does Microsoft support Exchange sites that use Sybari Software's Antigen or not? I keep seeing conflicting reports.

My opinion is that Antigen is a good product, and I'm not aware of any reports of it causing problems with Exchange. However, just like any other third-party software, when you put anything other than Exchange on your Exchange server, you are increasing the risk of a failure. According to the Microsoft article "Understanding How Sybari Antigen Software Interacts with Exchange Server" (http://support.microsoft.com/support/kb/articles/q250/5/00.asp), Microsoft Product Support Services (PSS) can ask you to disable Antigen. If you disable Antigen and the problem recurs, you can enable it and PSS will support you as usual. If the problem stops when Antigen is disabled, you need to contact Sybari's tech support and work through the problem with them. For further information about Antigen, see Tony Redmond's Windows 2000 Magazine article "The Great Antivirus Crusade," (April 2001).