When users send messages to some addresses the following error is returned
Your message did not reach some or all of the intended recipients.
The following recipient(s) could not be reached:
"destination e-maill"' on 10/30/2008 10:17 AM
You do not have permission to send to this recipient. For assistance, contact your system administrator.
<KTPO04.ktpo.ops #5.7.1 smtp;550 5.7.1 Client host rejected: cannot find your hostname, [our e-mail server address]>
We use Exchange 2003 on a MS Windows 2003 SP2 server