I have just been clobbered by PAYPAL direct!
I sent an item abroad using airmail, and at the buyers request the item was not sent international signed for to which I offer in all my auctions and state I do not take responsibility for lost items not sent as such.
The item was apparently not received and went to the resolutions centre. I sent them my proof of postage. Received email saying this is insufficient to track the item and PAYPAL gave them a full refund from my account.
Not a happy man!