I use certified mail to send demand notices to crooks in order to have the receipt showing I sent the notice to the last known address. I have learned if you want to loose a piece of mail, send it certified mail. I have had good luck with priority mail but prefer UPS or FedEx for the important and valuable shipments. My experience with trying to collect on USPS insurance claims has been the USPS claims sender negligence and inadequate packaging and rejects the claims. In most of those rejected damage claims, I think the USPS was correct about the negligence and inadequate packaging by the sender.