A USPS Flat Rate Box offers one low flat rate, so pricing is determined by the size box you choose rather than the weight of the box or the destination of the package. More »

www.reference.com Business & Finance Mail & Shipping Postal Services

As of 2015, the U.S. Postal Service offers two sizes of flat-rate boxes for Express one-to-two-day delivery. It also offers five sizes of flat-rate boxes for Priority one-to-three-day delivery. More »

United States Postal Service regional-rate boxes differ from standard flat-rate boxes in one major way. The costs for regional-rate boxes depend on the size of the box and the shipping zone, rather than having a single f... More »

www.reference.com Business & Finance Mail & Shipping Postal Services

The U.S. Postal Service calculates the cost of shipping for a package based on the package's size, weight and destination, as well as the specific mailing service the sender selects. To help senders estimate rates, a pos... More »

www.reference.com Business & Finance Mail & Shipping Postal Services

The differences in U.S. Postal Service shipping prices are due to the size of the package, the type of service the person is choosing and the distance to the mail's destination. The weight of the package also plays a rol... More »

If a package is undeliverable, the USPS returns it to the sender. The post office sends packages which are both undeliverable and not returnable to the sender to dead mail for further processing in order to return them t... More »

Though the exact length of time varies based on the package's contents and the chosen mail service, as of April 2015, USPS holds certified mail, insured parcels and ordinary parcels for 15 days after the first delivery a... More »