Answer
GMS will accept a message from a robot or executable and automatically queue it for delivery. It will accept the message on STDOUT and look for the To:, CC: and BCC: clauses (the latter will be removed automatically by GMS). In this case, GMS could not find any destinations to send the message to.
In this case session Undefined was processing a message from a server/client at Undefined apparently from Undefined to Undefined. The robot was executed and produced an email message with no recipients. The message as sent to Undefined.
This is the correct result, this is not an error within GMS. The robot will need to be modified not to correcly produce a message with To:, CC: or BCC: clauses.
See Also:
Keywords:robot recipients CC BCC To 8261