What if a buyer does not receive an item I sent? How can I prove that I sent it?
One way to show proof is to use a carrier with online tracking. For transactions involving merchandise worth up to the coverage amount (or the equivalent in the currency of the transaction) or more, keep an online receipt in the form of a signature from the recipient as proof of posting.
To view the specific terms and conditions, click Legal located at the bottom of any PayPal webpage.