Find a delegate in Outlook from Active Directory

The problem occurs when one of the employees that was configured as a delegate (for example user A) has left the company. When user B sends a meeting request for the manager, user B will receive an NDR because user A no longer exists in Active Directory, but is still configured as a delegate for user B.

The answer is here.

Phantom Recipient in Outlook Meeting Request

A user emailed me that she was sending a meeting request to another user via Outlook but it bounced because it was also being sent to a user who was no longer in our system.

It turned out that the recipient's Outlook client Tools, Options, Delegates still had that old user listed, which was then removed.