You might have seen your parents give a letter to someone who is going abroad so that they can pass it on to your relative who lives there. 
Well, in earlier times, when there were no postal services, this was how letters and messages were sent. This method of using travelers to deliver messages to other places developed into a system known as post riders.So we can say post riders were a horse and rider postal delivery system that existed at various times and various places throughout history. Post riders collected and delivered mail over the course of their route, meeting with other riders at scheduled times and scheduled places. Letters and parcels would be exchanged and forwarded to the next place by the riders. In this way, messages could pass a considerable distance
