When the Symantec Messaging Gateway delivers a message to another Message Transfer Agent (MTA) and sends the QUIT verb, it then attempts to close the network connection immediately rather than waiting for the remote server response to the QUIT command. This action results in the Symantec Messaging Gateway sending multiple reset (RST) network packets as the remote MTA responds to the QUIT verb after SMG has already sent a RST.
The action described above does not typically have any negative affect on the delivery of email, but can be noticeable as problematic behavior to network monitoring tools.
This issue has been addressed with the Messaging Gateway 10.6.2 release.
Please see the Messaging Gateway Administration Guide for detailed instructions on how to update the SMG software.