You seem to be trying to route this through the local host, 127.0.0.1 and so you may need to adjust the sendmail.cf file, usually found under /etc somewhere (use find /etc -name sendmail.cf)
Within this file, find and uncomment the DS statement. It sould have the format:
#
#
DSmymail.router.company
#
#
This would need to be your local mail server and that would need to have whatever routing rules to allow you to send through it. Often these are open, but many companies shut them down to avoid sending vast amounts of spam if a desktop is compromised by a virus.
Best to use a DNS name that resolves the IP address. You may need to stop/start the sendmail service to activate the update.
You also need to check that there are no blocks on your path the the mail server. Try a
telnet mymail.router.company 25
You should get output like:
If you don't then a long delay suggests wrong IP address, firewall block or wrong routing information in the network. A fast rejection may suggest that this is not the mail server.