A user has a Shared mailbox that they have full control over and Send As permissions. When she sends as this account(SS Sporting Team) it fails with the error below.
I have done the troubleshooting from the this link:
I forced a redownload and deletion of OAB.
I also recreated the profile on a user’s computer for one user y nada.
The user complains that all 3 people who have access to this mailbox receive the error they cant send as the shared mailbox.