Forest A containing Active Directory Domain & Exchange 2003 Front End and Back End Forest B Containing Active Directory Domain and Exchange server 2007 "2 Hub/CAS NLB, 2 MBX CCR and 2 Edge servers. a trust relation ship has been created between the two forests forest A and forest B containing the Same users "the administrator created the same users in both forests so he created the users twice. users logon to Domain B to access the Bank application and uses Domain A only for mail accessing so Exchange in forest B is useless. but the customer need to migrate mailboxes to Forest B and demote Forest A. so do i have to gradually user by user in Forest B and then use ADMT to migrate the deleted user from Forest A to Forest B then use ILM to create this contact on the other Forest. please provide me with your advice