I am having issues when I start to migrate 2 separate domains into one.
We will call them Alpha, Beta, Omega
Omega is suppose to be able to be authoritative over the mail addresses @alpha.com and @beta.com
The issues we are having is that after we move a mailbox from Alpha Exchange 2003 to Omega Exchange 2010 if a user still on Alpha e-mails someone whose has been moved to Omega but still uses email@example.com on Omega - Exchange loops the e-mail somewhere and gives us the error:
A configuration error in the e-mail system caused the message to bounce between two servers or to be forwarded between two recipients. Contact your administrator. The message is from the Alpha Exchange Server.
I am sure there are no duplicate addresses left on Alpha Active Directory. I removed the existing exchange attributes for Alpha Users and set a SMTP Address for them.