I am working on an Exchange 2010 migration from Exchange 2007 and come across the following difficulties:
1. The domain where the Exchange 2007 and the new Exchange 2010 (e.g. ABC.org domain) sits in a different domain than the domain that the Windows NT users log on (e.g. ABCinc.org domain). For users to log in the network resource domain (ABCinc.org) and check their Outlook emails, currently the network admin has to create the same user account twice --- one for each domain. Then link the mailbox to the user AD account;
2. Exchange 2010 seems working just for the mailbox account, it appears on the Exchange 2010 server when you created the mailbox from the exchange 2007; but not the other way around --- users can not access their email if the mailbox is created on the Exchange 2010 server first.
3. What is the best practice to resolve the AD domain trust issues?
4. What is the best practice to migrate the current Exchange 2007 to Exchange 2010 based on the above scenario?
5. The final goal is to merge the two domains together and use the Exchange 2010 for email access (including decommission the Exchange 2007 server).
Thank you for your help in advance.
BTW, all AD servers and both Exchange servers are VMs from VMware.