Hi Hernan
As this link said, you can`t directly generate a message when save MIGO.
you need some enhancement in MIGO.
please refer this link:http://benxbrain.com/en/index.do?onInputProcessing(brai_object_thread)&001_threadid=0000167461&001_boardtype=01&sysid=WP5&pgmid=R3TR&object=TRAN&obj_name=IDOC&child_param=
hope can help you.
Regards,
Archer