One of our Exchange servers in our organization started behaving badly 2 days ago, and we've done most everything we can think of to get it working fully again. To my knowledge, nothing in the environment has changed (with the execption of things we've done to troubleshoot this).
We have many Exchange 2k3 servers (About 50) in our org, and all are set to relay all messages through two primary COM Servers. Thos COM Servers are set to relay the messages out to the web. Everything works great, with the exception of a single server.
The Exchange server that's having the problem, only did so within the last 2 days, and was previously working fine.
Users behind the Exchange server with the problem attempt to send messages to an external domain, and are given an NDR by the local *broken* Exchange server saying that they don't have permissions to send to that recipient (Exact message pasted below).
Keep in mind that this server worked fine a little over 2 days ago, and to my knowledge - nothing was changed.
I've checked the SMTP Virtual Server settings, and connector of the Exchange server. It's routing * SMTP up to the COM servers. The COM servers also have an IP exception for that particular server to allow relay.
Would anybody know an area I can check to see what's happening on this server?
Your message did not reach some or all of the intended recipients.
Subject: RE: ****
Sent: 9/28/2011 7:08 AM
The following recipient(s) cannot be reached:
'****' on 9/28/2011 7:08 AM
You do not have permission to send to this recipient. For assistance, contact your system administrator.
<SERVERNAME.DOMAINNAME #5.7.1 smtp;550 5.7.1 Unable to relay for ExternalMailAddress@domain.com>