Puntuado con 4 de 5 estrellas

Does what it says, just add the button to the message editor and hit it. Sender and receiver are filled in automatically, if needed.

4/5 Stars, because it's missing a filter-action. This way you could autorespond to spams, your stalking ex-friend, or your business contacts.

Esta valoración es de una versión anterior del complemento (0.18.0). 

Thank you for the idea. I'll see if a filter action makes sense.