Currently working through a test of an Exchange 2003 to 2010 upgrade. Couple of questions, that i seem to find varying answers on... I have a 2003 DC, a 2012 DC, domain and forest functional levels of 2003, and Exchange 2003 already running. In running the first part of the upgrade the Exchange 2010 setup advises "Setup is going to prepare the organization for Exchange 2010 by using 'Setup /PrepareAD'. No Exchange 2007 server roles have been detected in this topology..."
My concern is whether this is likely to ill-impact the currently running Exchange 2003? I understand that Exchange 2003 does not support a 2012 domain or forest FL, but given the domain is still running in 2003 FL i would have thought this would not cause an issue.
Thanks in advance.