I have a client that has multiple email domains, 123.com and 456.com for example. The SBS Exchange server was receiving email for both domains and there were no issues. Now I have moved the 456.com email domain to a hosted Exchange solution.
I have gone into the SBS 2003 server manager and removed the 456.com smtp domain from the default recipient policy and then gone into each individual mailbox and removed the @456.com smtp address from each. I have changed the MX records to point to the new hosted Exchange server.
If email is sent from the Exchange 123.com domain to 456.com on the new hosted exchange server, the sender receives and NDL receipt stating that the user does not exist on the remote domain. SPF and PTR records have been changed as well.
Help is desperately needed. TOP POINTS given.