Hello All,We are running Exchange 2003 sp2 on Win 2003 sp2 (single server) and are experiencing an issue where email is working correctly except for a single domain. When our users send to this domain, they receive the notification: This is an automatically generated Delivery Status Notification. THIS IS A WARNING MESSAGE ONLY. YOU DO NOT NEED TO RESEND YOUR MESSAGE. Delivery to the following recipients has been delayed.Additionally, the mail to this domain gets stuck in an outbound queue in the retry state and remains there. Forcing connection does nothing. No timeouts, no errors in the event logs.We have confirmed that dns/nslookup works properly, I can telnet to the domain over port 25 properly, we are not on any blacklists.Any suggestions are welcome.Thanks in advance!!!

Have you tried a trace route to that domain? I had a similar issue recently and was getting stopped at a particular hop.

Thanks everyone for their responses.I ended up figuring out the issue, but should have done so before I posted - so my bad. When telnetting over port 25 to the domain, I entered ehlo to which I received a response. At that point, I mistakenly assumed that connectivity was OK. Upon running all the commands later, after the mail from: command, I received an error: 403 4.7.0 encryption too weak 0 less than 128. From this we determined that they are requiring TLS to communicate which we don't have enabled on our server, so we had to route it through a different location that does have it enabled. At that point, all emails went out.