There are some random messages are being stuck on Notes server. The messages are 20-30k in size. Message Connection Inactivity time is set to 45 seconds.
CMN waits for the SMTP server to terminate the message. CMN is not receiving "dot" and the watchdog kicks in and kills the connection.
1- Verify Cisco firewall SMTP Fixup is not being run over the Notes server that the messages stuck.
2- Verify no other Fixup utility is being run that will queue the messages.