I have created a new shared mailbox on my Exchange 2013 server in the building here. I have given several people FULL access to the mailbox and at least two users SEND AS permissions.
When I opened my Outlook, the shared mailbox shows up just like it should and mail flows into the mailbox. However, when anyone tries to send as from the mailbox by changing the FROM address, it fails and the message is that "You do not have permission to send the message on behalf of the specified user."
This seems like such a simple and straight forward thing, but clearly I am missing something. Can anyone assist?