With the release of Exchange Server 2010 SP3 Update Rollup 5 we now have support for running Exchange Server 2010 in Windows Server 2012 R2 Active Directory environments.
To be clear, this means that the following is supported with Exchange Server 2010 SP3 RU5:
- Active Directory Domain Controllers running Windows Server 2012 R2
- Active Directory Forest Function Level and Domain Functional Level of Windows Server 2012 R2
The following is not supported:
- Installing Exchange Server 2010 SP3 RU5 on a Windows Server 2012 R2 server
So in other words, Exchange Server 2010 is no longer a roadblock to an Active Directory upgrade to Windows Server 2012 R2.
More information is available at the Exchange Server Supportability Matrix.