Recently one of our vendors made a change to their email system and I'm unable to send messages to them. I get the following error returned by their postmaster.
You do not have permission to send to this recipient. For assistance, contact your system administrator.
<EMAIL SERVER NAME #5.7.1 smtp;550 5.7.1 Unable to relay for NAME@DOMAINNAME>
I'm on Exchange 2003 running on Windows 2003.
BTW...no problem when I route the message thru our POP account.
Any workaround you can recommend?