I agree with Greekbaby. According to PayPal's rules, the seller is responsible even if the buyer does not purchase insurance. Insurance protects the seller if the item is damaged, lost, stolen, etc. If no insurance is purchased and the buyer files a PayPal claim, the buyer can get their money back.

Also, the USPS delivery tracking number is not real tracking, like what you get with FedEx & UPS. The USPS delivery tracking number is generally only scanned when the packaged is delivered. The Post Office is not required to scan the delivery tracking number when you drop it off. If you want real proof that you dropped off the package, you need to purchase delivery confirmation at the Post Office counter and pay the 55 cents or whatever it costs now. I hope it works out for you!

ITA!