Question: how much does it cost to send a letter overnight through the post office?
Answer: Overnight delivery is available to most U.S. addresses and PO Boxes™2 with a money-back guarantee1. With our free Flat Rate Boxes, you don't need to weigh shipments 70 lbs and under. Purchase Priority Mail Express postage and shipping labels at a Post Office™ location or online. Prices start at $26.35.