Mailing your intellectual property to yourself: Does that REALLY work?
When discussing copyright protection, sooner or later someone's going to suggest mailing your intellectual property to yourself as an easy way to protect what's yours. The "Poor Man's Copyright," as it were. So, does this actually work, or is it just something that "sounds right," so people love to share it?
The truth is that there aren't really any advantages to mailing something to yourself. If you create something, be it a corporate logo, a blog post or a t-shirt design, you own it the minute you're done creating it. These days the chain of evidence leading to the originator is incredibly strong, as there is an imprint of your work the minute you set out to write the first page of your novel or take a photo with your phone. It's very difficult for IP thieves to claim the copyright on something that they did not create. If you've created something, then you probably have all the evidence you need to put a stop to anyone who would take it for themselves.
Registering your work is not an issue of protecting it so much as establishing your right to pursue damages should somebody else use your intellectual property for their own game. You're not going to have an easy time pursuing statutory damages on, say, a screenplay, if it's not registered with the Writer's Guild of America. You may still be awarded your damages in court, but that's going to cost you in legal fees that will ultimately outweigh the cost of registration.
Once upon a time, patent laws worked on a "first to invent" rule. So a long time ago, it made sense for a chemist or an engineer to mail themselves blueprints and schematics for whatever it was they were creating. It certainly would have saved Tesla a lot of trouble with Edison. But when it comes to patents in the modern day the rule is "first to file," meaning that you do not have any patent protection without seeking, well, patent protection.
So, to make a long story short: Mailing intellectual property to yourself is a waste of a stamp. The protection that you think you're getting when you do this is protection that you already have the minute you write your idea down in a memo pad, and any additional protections cannot be had without registration through a patent office or a guild of some sort.