Sending Money Through The Mail - Proof?

I'm thinking about buying rsgp through sending money in the mail but I am wondering what's stopping the seller from claiming I never sent him the money. What would be valid proof to provide for this type of transaction?

 

Basically it's impossible to prove. Only do mail transactions with people who have done them before and you trust a lot.

 

Add a tracking number for 70 cents... It tells you when it leaves the post office, every stop, to when its delivered.

 

That doesn't prove what's in the package..

 

Use a Money Order or Certified Check, and bam, you have your proof.

 

Both are pretty low-cost and safe, but I wouldn't trust them with any larger trades.

It would be near impossible to catch a counterfeit and the mistake might not be discovered until your bank does weeks later and the money disappears from your account.