http://blogs.technet.com/jkruse/archive/2006/11/24/exchange-2007-tip-o-the-day-not-updated-daily.aspxWhen you install Exchange 2007 for the first time, you need to extend the AD schema (usually by running setup.com /PrepareSchema , or just setup /ps if you’re lazy like me). Make sure you do this in the same AD site as the schema master, otherwise youen-USCommunityServer 2.1 SP1 (Build: 61025.2)