http://blogs.technet.com/mbaher/archive/2009/06/17/common-unsupported-exchange-2007-configurations.aspxThis is an interesting section in the Exchange 2007 help file that i wanted to share and recommend you to read it,   http://technet.microsoft.com/en-us/library/dd577077.aspxen-USCommunityServer 2.1 SP1 (Build: 61025.2)