Consider the following scenario:
Users in a cross-forest environment are migrated from one exchange server in Domain A and must connect to the new exchange server in domain B with their new credentials. Their AD attributes gets changed in the migration process to contain their new email address from domain B, however user’s workstation are still in logged-in domain A. The users create a new mail profile in Control Panel -> Mail and the auto-discover account setup wizard shows up pre-populated with their email address from the domain and the password fields are hidden.
The problem is: The users does not enter their new password or change the email address and click next, the auto-discover tries to authenticate with their windows credentials from Domain A to domain B and authentication is failing. A credentials prompt shows up containing the wrong email address (legacy from domain A) and the confused users enters is old credentials. Since there is no trust being the domain A and B, authentication fails over and over again until their account gets locked.
The best solution would be to show up the autodiscover window without pre-populated fields or pre-populated email address with the password field visible EVEN if the user is connected to a domain. Well that's possible using a registry key, here's how (where %v% is the outlook version):
VALUE : 0
Deploying this key by GPO or with a custom script will disable the active directory lookup in the wizard. See this technet for more information :
I hope this is as helpful to you as it was to me,