Looking at this from the perspective of a customer, I would personally assume the risk if I used Paypal f&f. I understand there is a risk going into the transaction this way. When the postal/shipping service receives the item, the seller is absolved of responsibility for the package. It would be kind, and expected, of the shipper to help with filing lost package claims and things like that, but the seller completed his or her end of the transaction. Your concern should be with the shipping company, and demanding an adequate response from them. That's how I look at it, anyway.