I am getting a bounceback when sending an email from another account, the error is "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 problem is I am not trying to send on behalf of any of the bounceback addresses, I am trying to send TO them. I have enabled "Send-As" and "Full Access" permissions to the account.
The message will successfully send to all recipients if I put all the addresses in the "CC:" field with no adresses in the "TO:" field, as soon as I put an address in the "TO:" field it will bounceback from ALL the addresses including the ones in the "CC:" field.
I have tried this on the users machine and my own machine with the same result.
Any ideas??