Have a weird issue I can't determine how to fix, and whether it's AD, Exchange, a bug in either or what.
But User A is trying to send to a Distribution Group "from" User B (User A is putting User B in the "from" box, and putting the Distribution Group in the "to" box).
When User A sends the e-mail, they get a bounce-back error:
From: Microsoft Outlook
Sent: Friday, February 28, 2014 10:57 AM
To: User A
Subject: Undeliverable: My Parents 2014
Delivery has failed to these recipients or groups:
You can't send a message on behalf of this user unless you have permission to do so. Please make sure you're sending on behalf of the correct sender, or request the necessary permission. If the problem continues, please contact your helpdesk.
I have verified in the Exchange Console that User A has "Send As" permission on User B, and that User A is listed as a Delegate in User B's Outlook > File > Account Settings Delegate > Delegate Access.