What is the origin of the letter?

What is the origin of the letter?
Pre 1653 messages were sent but were not called "letters". these were normally strategic communications between high ranking people. There are many records of the Romans and Egyptians passing information in this manner.

In 1653, Frenchman, De Valayer established a postal system in Paris. He set up mail boxes and delivered any letters placed in them if they used envelopes that only he sold. An enemy put live mice into the letter boxes and ruined De Valayer's business

A schoolmaster from England, Rowland Hill invented the adhesive postage stamp in 1837, an act for which he was knighted. Through his efforts the first stamp in the world was issued in England in 1840. Hill created the first uniform postage rates that were based on weight, rather than size. Hill's stamps made the prepayment of postage both possible and practical.