We have forwarding disabled. When user2 needs to receive email for terminated user1, we do the following:
-- Rename user1 to user1_archive.
- Create an alias for user1 that points to user2
- Configure User2 with Outlook connections to her own account and user1_archive.
We should also disable SMTP In fro user1_archive, to protect from spammers stun long on the account, however unlikely.
I think this approach will be processed as one delivery step rather than two, so your current problem will be avoided and the processing time will not be wasted.