In mail, there's two to's:

The message to and the envelope to.  If you don't set them
both you can get hijacked by various mail server's configuration.

Ticket: #6005

(Yes, I did just make you say tutu.  If you look under there you
might find the answer)

(Yes, got you again.  I just made you say underwear)

(cherry picked from commit 98078c1e87f51110e51861b8f5f9fa35b3753cd8)