how does the "copyrighting something by mailing it to yourself" work?

Question

I was told by a friend that all i have to do to copyright any of the things i've written (cheap and easy) is to mail it to myself.
But how exactly does this work?
How does that prove that the peice of paper inside the envelope was from that date, if someone could just put any peice of paper in the envelope.
I'm sorry if i sound stupid, i'm just a little confused.

Answer 1

allegedly it proves the date you came up with an idea - that is if the letter is in there - and the postal service gives a clean date mark - front and back to seal the letter -

do not know if it will hold up in court

and do not open the letter

Answer 2

Tom's answer is correct as far as it goes. However, it is also necessary to make a formal application for a copyright. (The unopened letter/copy to yourself is only a back-up.)

Answer 3

If you are try to copyright something the best advice is to get come professional assistance. There are norms which you must observe, and, the best advice comes from someone who really and truly knows the subject.