Well, SMTPdebug level 3 only gets me this info:
[0C04:0006-0D2C] 04/27/2016 09:02:31.26 AM SMTP CIServ Listen> Connection Accepted on Port 25 for Session 234A2E6D
[0C04:0008-0FF0] 04/27/2016 09:02:31 AM SMTP Server [0C04:0008-0FF0] State change from Greeting to Greeting
[0C04:0008-0FF0] 04/27/2016 09:02:31 AM SMTP Server [0C04:0008-0FF0] Processing in Greeting state
[0C04:0008-0FF0] 04/27/2016 09:02:31 AM SMTP Server [0C04:0008-0FF0] State change from Greeting to Connected
[0C04:0008-0FF0] 04/27/2016 09:02:31 AM SMTP Server: xxxx.xxxx.ca (127.0.0.1) connected
[0C04:0008-0650] 04/27/2016 09:02:35 AM SMTP Server: xxxx.xxxx.ca (127.0.0.1) disconnected. 0 message[s] received
It looks like there is a connection being made on port 25, but no data is transmitted?
On a normal inbound SMTP connection, I get this:
[0C04:0006-0D2C] 04/27/2016 09:02:44.40 AM SMTP CIServ Listen> Connection Accepted on Port 25 for Session 234A2E6F
[0C04:0008-0650] 04/27/2016 09:02:44 AM SMTP Server [0C04:0008-0650] State change from Greeting to Greeting
[0C04:0008-0650] 04/27/2016 09:02:44 AM SMTP Server [0C04:0008-0650] Processing in Greeting state
[0C04:0008-0650] 04/27/2016 09:02:44 AM SMTP Server [0C04:0008-0650] State change from Greeting to Connected
[0C04:0008-0650] 04/27/2016 09:02:44 AM SMTP Server: mail6.bemta8.messagelabs.com (216.82.243.55) connected
[0C04:0008-0FF0] 04/27/2016 09:02:44 AM SMTP Server [0C04:0008-0FF0] Processing in Connected state
[0C04:0008-0FF0] 04/27/2016 09:02:44 AM SMTP Server [0C04:0008-0FF0] EHLO command received