Exchange 2010 times out (Primary Target IP responded with:"421 4.4.1 Connection timed out.") when sending to military emails. Restarting these directly through the Exchange Admin Console eventually works, but I can't babysit the server.
Send connector address space is just * with cost set to zero so all mail gets the same priority. Have tried creating a custom send connector with same result.
Set inactivity timeout on connector to 15 mins.
Restarted Exchange Transport and other relevant services as expected after any config changes.
nslookup from server resolves DNS (MX records) for recipient(s)
Talked with someone inside a military base. His suggestion was to try and send through OWA. Sent him an email through Outlook/Exchange and another through OWA. Both are sitting in the outgoing queue waiting to try, then timeout again.
These are set to retry every 10 minutes. If left alone, they hang in the queue, send NDRs to my boss and usually fail in 48 hours. Once she gets an NDR, I get a message to do something and restarting (just right-click "Retry") eventually gets them sent though it may take one or ten tries. I welcome another set of eyes. This has been the norm for about 6 weeks and nothing I can think of changed on our end. Thanks! :)