Primitive message systems have been in place as long as man has been in existence. Until 1840, however, regardless of how primitive or how elaborate, all these systems operated without the benefit of a postage stamp.
In the early days of the postal service, stamps and envelopes did not exist. (For the most part, envelopes were not used because they were considered to be an additional sheet of paper which cost more to send.) When you wanted to send a letter you would fold it up and seal it shut, and the person who received the letter had to pay for the delivery costs. Since rates at that time were very high, many people refused to accept letters. In fact, many people developed secret codes by which they could cheat the postal services. They would place secret marks on the outside of the letter that conveyed their message and all the addressee had to do was read the secret message, refuse to accept the letter, and thus not have to pay for it. Mainly for this reason, postal services turned to a means of prepaying postage.