I am having an issue with our email getting stuck in the 'Internet Mail SMTP Connector' queue. We are running exchange 2k3 SP2. Our Exchange server is setup to forward all emails to our email filter appliance which is setup as a smart host in the Internet Mail SMTP Connector Properties dialog box and is on the same switch and subnet as the server. I have already rebooted the filter appliance twice, and confirmed that there haven't been any configuration changes. When i look at the properties of the queued email I notice that it shows thousands of 'Delivery Failures'. I did some packet captures and found that the exchange server is sending quit messages after receiving a response to HELO.
What can i do to resolve this?
Thanks for any and all help!