'If an error occurs before a mail message is sent sendError will be
called.  This base class method sends a QUIT if the error is
non-fatal and disconnects the connection.
@param exc: The SMTPClientError (or child class) raised
@type exc: C{SMTPClientError}'

def sendError(self, exc):

    if (isinstance(exc, SMTPClientError) and (not exc.isFatal)):
        self._disconnectFromServer()
    else:
        self.smtpState_disconnect((-1), None)
