How can I migrate NT 4.0 users to Windows 2003 Active Directory? Originally, we had four NT. 4.0 domains but I upgraded the first domain to 2003 Active Directory. Our network is currently running in “mixed mode”. I am trying to migrate my other users who still belong to the remaining three NT 4.0 domains to Windows 2003 Active Directory. I want to do this because I will be able to use the “move mailbox wizard” in AD to move their existing Exchange 5.5 mailboxes to Exchange 2003. I tried using the Active Directory Migration tool (ADMT) but since we are running in “mixed” mode and not “native” mode, the ADMT will not allow me to move the NT 4.0 users to AD.