Comment by rgblambda

Not that I don't take your point that such a service could exist, but the site you linked explicitly says they don't offer letter writing as a service.

Also, I imagine it's not impossible to reliably distinguish between an autopen and genuine handwriting. The company who's site you linked say their machine can't perform complex pen movements so calligraphy is impossible.

The real advantage of posting a letter is that you have to pay for postage, and the stamps on the envelope will indicate which country the letter is really coming from.