For want of a nail, the shoe was lost;For want of the shoe, the horse was lost;For want of the horse, the rider was lost;For want of the rider, the battle was lost;For want of the battle, the kingdom was lost;And all for the want of a horseshoe nail.
The above poem is about the cause and effect theory, it demonstrates the need of the courier to deliver the message, and the need of the sender to get the message delivered. (In this case to avoid the loss of Kingdom)... Hopefully the messages and packages that you send via a courier, if not delivered on time, will not be as catastrophic.
Historically st courier tracking - protrackinghub.com have used all modes of transport including; runners, homing pigeons, horseback riders, and foot messengers to name just a few. Foot messengers would run for miles to reach their destinations. Apparently some of the routes they used are directly related to marathons.