Absolutely great.
Wrong section and mass-mentioning :/
The fact is, you can't prevent a PayPal chargeback from happening, having the buyer write a note like "I have received my goods and I will not dispute this transaction" doesn't get you anywhere either.
The only 'real' solution, but requires you to trade with an Official Middleman, would be having the buyer open a dispute right after the transaction and immediately close it again. (A dispute can only be opened once per transaction)