Herodotus on Mail

“Neither snow, nor rain, nor heat, nor night stays these couriers from the swift completion of their appointed rounds.”

“It is said that as many days as there are in the whole journey, so many are the men and horses that stand along the road, each horse and man at the interval of a day's journey; and these are stayed neither by snow nor rain nor heat nor darkness from accomplishing their appointed course with all speed.”