Hi,
We are doing a cross forest domain migration where both Forests have their own Exchange environments. The source domain is running Exchange 2007 SP2 and the Target is running Exchange 2010 SP3. All is setup and ready to go but we were asked if it were possible to allow users who have been migrated, along with their machines and their mailboxes, to be able to still login to their computers as well as their Outlook clients using their source domain credentials. This would just be for a period of time to "soften the blow" of all the changes that are taking place. We would maintain the Source domain for a period of time and then remove the trust and decommission it.
We have the MEU account created in the target first, then ran ADMT, then migrated the machine and the mail so they are 100% in the target domain, but SID History has been enabled. A migrated user can still login to their machine with the Source domain credentials, no problem. But when you launch outlook it wants them to authenticate to the CAS that is in the Target domain. This is all very logical.
Is it possible to allow them to use the old credentials? I have tried to Add-mailboxPermission unsuccessfully. I have read some posts about removing the SID History attribute and how that solved the problem, but I haven't tried it yet because I think we may need SID History for accessing Source resources and that it may affect login with the old credentials (not sure).
I have also read about Linked Mailboxes but that doesn't seem like what I want if I am migrating the users along with the mailbox.
Anybody have an answer?