Messages from a particular source or domain are accepted by Messaging Gateway (SMG) but a specific message always fails to be delivered with a message indicating that the message delivery timed out.

421 4.4.2 service timed out

When processing a specific message, the SMG mail service does not respond to the end of the message resulting in an SMTP session time out.

This is a known issue with a very specific and limited message format and does not generally affect Messaging Gateway's ability to accept and deliver SMTP email.

This issue has been resolved with the Messaging Gateway 10.7.4 release.