Here's a short, educational movie about how the mail gets from one place to another, via trucks, trains, planes, helicopters, and eventually the mail carrier; this movie being from 1963, the guy is called the mail man.
It's a potentially interesting subject, as shown by the 1936 NIGHT MAIL. That was made by the GPO unit that later turned out amazing wartime documentaries, and the folks in charge of that movie wanted to make something that was not only informative, but interesting for the audience. This one is made for children, and made for children by adults who think that children are idiots, with the unnamed narrator -- I wouldn't give my name either! -- speaking in the tone of voice you usually reserve for people who won't understand what you're saying anyway.