I am getting a “no messages transferred to …com” but without any explanation that I normally see when this happens. I can telnet to both domains via port 25 successfully.
Any ideas?
Subject: mail not routing to certain domains
This might help:
http://www.ns-tech.com/blog/geldred.nsf/d6plinks/GELD-7C353H
Gregg
Subject: RE: mail not routing to certain domains
Thanks for info.
After running a trace route and getting several timeouts. I added the debug parameter.
I got “Connection terminated with status: 2562”
The strange thing is this. We are attempting to send an email from an app on another server. These are the emails that won’t route.
I sent an email to the same domain using my address and, after several attempts it did go through. The other emails are still sitting in the router.
Subject: RE: mail not routing to certain domains
“The other emails are still sitting in the router.”
On that server, where the messages are stuck, go to the Domino Console. Type:
tell router sh
Then press enter.
The Router will show you why those messages are still in the queue. Hopefully, it will tell you something useful. 
Subject: RE: mail not routing to certain domains
Hi,status: 2562 indicates, it is not a issue between smtp-sender and smtp-receipient.
Usually status:2562 only occurs on mails with attachment and meens smtp-transfer is broken by firewall or anti-virus-software.
Most common reason for this is a missconfigurated intruser-detection-rule on receipients side.
HtH
Heinz