how late will usps deliver

USPS delivers mail and packages until around 6 PM on Sundays. For Priority Mail Express, Sunday deliveries are guaranteed by 10:30 AM, with a refund if delivery is later than 6 PM. Amazon packages delivered by USPS on Sundays can arrive as late as 8 to 10 PM depending on the location and volume. Regular mail delivery on Sundays is very limited and mainly reserved for Priority Mail Express and Amazon packages in metro or high-volume areas.