A worldwide postal organization to which most countries are members. The exchange of mail, except parcel post, between the United States and other nations is governed by the provisions of the Universal Postal Union conventionJoint Publication 1-02 U.S. Department of Defense Dictionary of Military and Associated Terms; 12 April 2001 (As Amended Through 14 April 2006)
The Universal Postal Union (UPU, French: Union postale universelle) is an international organization that coordinates postal policies between member nations, and hence the world-wide postal system. Each member country agrees to the same set of terms for conducting international postal duties. Universal Postal Union's headquarters are located in Berne
UPU, international specialized agency of the United Nations formed in Switzerland in 1875 that administers and governs international postal service (formerly was called "General Postal Union")