We have an Exchange 2003 Organization on the Domain and now all Domain Controller of the Domain has been upgraded to Windows 2008R2. Is Exchange 2003 compatible with the Domain Functionnal Level Windows 2008R2 ? Can I raise the functionnal level of the Domain to Windows 2008R2 without negatif impact for Exchange 2003 ? Regards, -Misch-

As far as I know they are see below http://technet.microsoft.com/en-us/library/ff728623.aspx Sukh

Hi If your version of exchange is exchange 2003 SP2, you needn’t do anything. The answer of question 1,2 are Yes. If your version of exchange is exchange 2003 SP1 or other version, please update it first.