@Grivusangel -- Good Lord. That's everyone's worst nightmare, and well worth the extra couple of bucks to send something like that registered mail, return receipt requested. Either that or Fed Ex. I'd definitely send it by some method that provides a way to track the letter or get receipt confirmation.
If wiring money didn't cost so much, I'd be tempted to do that. Wiring it would be nearly as expensive as the ticket!
For some things -- especially legal documents -- you cannot be too careful. Anything can happen, and usually does.