The oldest known postal document, which was found in Egypt, goes back to 255 BC. But even before this time, postal services existed on almost all continents in the form of messengers in the service of kings and emperors. In the course of time, the religious orders and the universities established their own systems of message transmission, and later, individuals could also use the services of messengers to communicate among themselves. In these distant times the postal charges were generally paid by the recipient.

The first postal agreement was established in the 17th century. It was based on existing bilateral agreements regulating the carriage of mail between several European countries. Two centuries later, the network of bilateral agreements between the countries had become so complex that it had started to place obstacles in the way of trade and exchange which were developing rapidly. The national postal reforms marked the debut of a regulation and a simplification of international postal services.

The most important of these reforms was undoubtedly that conducted by Sir Rowland Hill in England in 1840. All letters of a certain weight destined for the inland service, whatever the distance, had to be stamped at a single rate of one penny. In 1863, a conference was held in Paris (France) on the initiative of the Postmaster General of the United States of America, Montgomery Blair, to try to pursue the postal reform process at an international level. Other attempts made up to the end of the 1860s to improve the international postal service on the basis of bilateral agreements had not managed to keep in step with the already rapid pace of the technological, economic, commercial and cultural developments. Heinrich von Stephan, chief postal officer of the Northern German Confederation, conceived then the plan of an international postal union. On the basis of his proposition, the Swiss Government organised a conference in Bern on the 15th September 1874 which was attended by representatives of 22 countries. On the 9th October, a date which has been subsequently celebrated throughout the world as world postal day, the Agreement of Bern was signed establishing the General Postal Union.