Answer
GMS was sending email to a remote messaging server when the remote server disconnected therefore GMS will requeue the messages and start sending them again later.
In this case, session Undefined had connected to Undefined (IP address Undefined) and was processing the folder Undefined. The remote server disconnected from GMS.
GMS will recover from the problem with the remote server, no action is required by you.
If the remote server persistently disconnects you may want to investigate what is wrong with it.
See Also:
Keywords:post disconnect restart retry 8385