Postal administration ...
From Wikipedia, the free encyclopedia

Postal Administration is an umbrella term used to collectively characterize all the functional entities within a country that participate in the regulation and operation of domestic and international postal services. The term is widely used in diplomatic documents and international conventions and treaties that establish relationships between countries involving postal services. The Universal Postal Union (UPU), established in 1874 by the Treaty of Bern and is now a specialized agency in the United Nations, is the international organization that coordinates postal operations between member nations. Each UPU member nation agrees to operate its Postal Administration according to a common, international set of rules for international postal services. Within the UPU conventions the term Postal Administration is used to identify a country that provides international postal services. Below is treaty language from the 1906 UPU treaty.

Postal Administration Service Sector ...
Found on 1800miti.Com, the Commerce Directory

The Postal Service Sub-Section includes the activities of the National Post Offices and their subcontractors in delivering letters and small parcels. These articles can be described as those that can be handled by one person without using special equipment. This allows the collection, pick-up, and delivery operations to be done with limited labor costs and minimal equipment. Sorting and transportation activities, where necessary, are generally mechanized. The restriction to small parcels distinguishes these establishments from those in the transportation industries.

Bulk transportation of mail on contract to the Postal Service is not included here, because it is usually done by transportation establishments that carry other customers' cargo as well.