I currently have two clustered Exchange 2007 Servers running the mailbox role, two other Exchange 2007 Servers running the Client Access and Hub Transport roles, and an Exchange 2003 Server. The Exchange 2007 servers have SP3 and the Exchange 2003 server has SP2. Our Domain level is currently Windows 2003. I am preparing to upgrade our Domain level to Windows 2008 R2. Will upgrading AD to 2008 R2 cause a problem with my Exchange Servers? Specifically, I want to check whether the Exchange 2003 Server will still function. I can decommission the Exchange 2003 Server if I have to, but I would prefer not to yet. Thank you very much.

Please look at the link below, http://technet.microsoft.com/en-us/library/ee338574(EXCHG.80).aspx Cheers EK

Thank you!