Using Exchange 2007
I've setup one user (domain admin) to have his email forwarded to his external gmail account (Mail Contact - > User Delivery Options) via Exchange Management Console.
It does work. If a internal user sends an email to the domain admins company mailbox, it does forward to his external gmail. Same results when someone from outside the company sends an email to his company account -> gets forwarded to his external gmail account. So the most important thing is that it works in both those scenarios. What's not working was discovered when we were testing the initial change. He, from his gmail account, sent a test email to his company email account and he did not get the forwarded email back on his gmail account. We spent quite some time thinking the external forward was not working but in actuality it was working, just not in the specific test scenario. I can't figure out why the forward is not working when he sends a test email from his own gmail account.
I've tried tests from a different gmail account and it does work. When he sends the test email from his gmail account it arrives in the system and does go to his company mailbox. Any ideas?