I have gotten these before, but not produced this way. The ones I got looked like they were written by an underpaid employee.
They have had signature machines for years though. The Kennedy's used them a lot.
The only thing I would experiment with this project is adding significant error, and randomness to the writing. It would look more realistic?
On a personal note, when I get these (Anderson Painting likes this approach.); I throw away the ad away immediately, or if printed on good stock paper--I save to pick up dust.
To trick people into opening their junk mail, because they think it's a letter from a human.