Prior to the first third of the sixteenth century messages were delivered as the need arose by envoys in the service of the crown or of institutions such as towns, guilds and schools. When the state postal service was introduced, with its regular exchange of horses, fixed relay stations and tariffs, it initially served the monarch, and only then the privileged classes and, eventually, the public at large. The advance of science and technology that began in the 18.th century brought progressive improvement in systems of delivery, with the coach giving way to the motor vehicle, the train, the telegraph, and...