GMS has been configured to manage Delivery Status Notification (DSN) messages. There was no DSN specification with this message so GMS has added it.
In this case session Undefined was receiving a message apparently from Undefined being sent by the machine at Undefined. The DSN details were added to the RCPT clause.
The missing DSN information has been introduced by GMS so no action is required by you. You may like to contact the owner of the domain at Undefined to let them know that their system is not processing DSN requests correctly.
What is happening in this case is that either a NOTIFY or an ORCPT DSN command were given as part of the ESMTP transaction but no parameters were supplied to these commands. As this is an invalid use of DSN GMS has automatically supplied default parameters for the commands as described below.
This is specified on the same line as the RCPT command, and requests that DSN notifications are only sent if there is a failure to deliver the message.
Again specified in the same line as the RCPT command the ORCPT is used to specify the original recipient of the message, the rfc822 parameter indicates it is the same as in the actual RCPT clause.
Keywords:DSN delivery status notification notify failure orcpt rfc822 RFC1891