The end user has send as and full access permissions on the mailbox in question. For some reason when she tries to send as in the from field she receives " 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."
The user needs to be able to send as no on behalf of.
Why is it that it keeps trying to send on behalf of?