GMS was operating the smart redirect rules and a rule indicated that further processing for that message by the redirect rules should be ignored.
The smart rules are processed in order until one of the rules are matched. Once a rule is matched it is immediately actioned and all processing of the smart rules are stopped for that message.
In this case, session Undefined was using the rule which matched the parameters
- Undefined = Source server/client IP address;
- Undefined = MAIL clause (the protocol FROM details);
- Undefined = Local IP address that the message was delivered to (this may be different for multi-homed systems); and
- Undefined = RCPT clause (the protocol TO details).