We have an issue where emails sent to aprox 30 different domains which use Symantec Message labs are expiring.
Sending Domain: epicassist.org
Sending IP: 22.214.171.124
Our mail server appears to keep an active connection to message labs for all the messages that it is sending then it eventually times out and expires. As this is the only mail system that we are having problems sending to it appears to be a message lab issue.