Good Evening, I'm running a mixed mode WinNT4.0 / Win2k domain with Ex5.5 installed (Exchange runs on a win2000 member server). My question is: If I want to upgrade the Ex5.5 to Ex2003 would I need to upgrade my domain also (I.e run the Master DC as a win2003)? If i don't have to - are there any issues with running the Ex2003 on a Win2003 member server in my current mixed mode domain. I'll really appreciate an answer please from all you lovely people out there. regards, Uche