Why is Exchange 2010 Queue Viewer showing multiple "No Sender <>" items that can't be delivered?
Posted on 2010-09-15
Microsoft Exchange 2010 server has been setup behind a Cisco Internet router with ACLs. Originally SMTP connections were allowed from any host on the Internet and a few other things may have been mis-configured. This resulted in the public IP address being listed on backscatter.org. Now obviously some domains are not accepting the connection attempts. The client is configured to have mail go through Postini first and now the router ACL has been reconfigured to only accept port 25 connections from Postini's public range. I have tested this from Postini's web console and it is working. Why is the server still trying to send out "Undeliverable" messages from no sender with obvious spam in the subject. I am aware that other messages are in there because we are on the blacklist. What is the best way to troubleshoot this? I have been manually clearing out the messages an not sending an NDR.