We are running Groupwise 6.5 on a Novell 6.5 server. The GWIA is set to
relay all outgoing mail through a sendmail server outside the firewall.
Everything will run fine for a couple of days then outbound mail stops
going. Looking at the sendmail logs we find this entry for every message
that is trying to be sent:

email1.rediker.com [xxx.xxx.xxx.xxx] did not issue MAIL/EXPN/VRFY/ETRN
during connection to MTA

The firewall is Border Manager 3.8 and it appears to be running. However
rebooting the firewall server often times will clear up the situation.
We need to know what is happening because rebooting the firewall is
causing problems with users being disconnected from their data.

I have asked in the GWIA forum and they directed me here saying it is
probably a problem with the SMTP Proxy.