A message was sent from an account on GMS to an external address but it was too large so GMS has sent a DSN error message back (as defined by Internet Standard RFC1894) to the sender of the message.
In this case, session Undefined was processing a message from a server at Undefined. The message was apparently from Undefined to Undefined and the error message was Undefined
This is the correct result, no action is required by you.
Keywords:DSN too large RFC1894 8290