USPS --The United States Postal Service (USPS) is an independent establishment of the executive branch of the United States government responsible for providing postal service in the US. Within the United States, it is ordinarily referred to as the "Post Office", "Postal Service", "U.S. Mail" or "USPS".
The USPS operates the largest civilian vehicle fleet in the world, with an estimated 260,000 vehicles. These vehicles are identified by a seven digit number displayed on the front and rear.
 

Parcelforce --Parcelforce Worldwide is a leading provider of guaranteed express deliveries covering all 27 million addresses in the UK and 99.6% of the world population.
 

DHL --DHL is the global market leader in international express, overland transport and air freight. It is also the world's number 1 in ocean freight and contract logistics. DHL offers a full range of customised solutions - from express document shipping to supply chain management.

EMS -- the international Express Mail Service is a special postal service offered by the postal administrations of the countries and regions in the world where EMS items enjoy the preferential treatment of the Post, Customs and airline companies. With the high speed and high quality, EMS transmits for the customers the urgent letters, documents, banking bills, samples and goods. Meanwhile, it provides online tracking and inquiry service by different ways. In addition, EMS offers some extended services such as agent of declaring, packaging and insurance.
Today,  EMS service has established service links with more than 200 countries and regions in the world.