On SBS 2008, I set the Full Permission and Send As permission on one user, giving another user full permission to send as the first user.
In Outlook, when the user tries to Send As the first user by using their username or email address in the FROM field, they get the following NDR:
Delivery has failed to these recipients or distribution lists:
You are not allowed to send this message because you are trying to send on behalf of another sender without permission to do so. Please verify that you are sending on behalf of the correct sender, or ask your system administrator to help you get the required permission.
I have NOT set the delegate permission as I heard that creates problems.
I have waited overnight for it to resolve. I have also restarted the server.
Any ideas of what I'm missing?