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

The United States Postal Service provides tracking options for most packages and letters shipped to Canada. The USPS does not, however, ship or track Priority Mail International Fat Rate envelopes or small Flat Rate ship... More »

The U.S. Postal Service sells envelopes in sizes ranging from 5-by-10 inches all the way up to 11 5/8-by-15 1/8 inches. Most of their envelopes are dedicated to Priority Mail for items needing urgent delivery. The Postal... More »

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 »

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 »

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 »