An «unknown user» or «no such user» or «invalid address» is usually a «550 5.1.1»
error message that will appear in your smtp
logs however, not all ISPs use the «5.1.1» extended reply
code, and not all «550» replies refer to unknown users.
One of the apps showed a list of
error codes and it was blank - so no, there were no
errors logged in OBD, the car was supposed to have no problem.