No matter what I do, I can not SEND AS a shared mailbox in Office 365.
I create the shared mailbox, add FULL and SEND AS permissions to a shared mailbox for any user.
The mailbox receives email, however that user can not SEND AS that mailbox.
I get this message no matter what
Your message did not reach some or all of the intended recipients.
Subject:
Sent: 5/17/16 10:14 AM
The following recipient(s) cannot be reached:
'user@gmail.com' on 5/17/16 10:14 AM
This message could not be sent. Try sending the message again later, or contact your network administrator. You do not have the permission to send the message on behalf of the specified user. Error is [0x80070005-0x0004dc-0x000524].