A postal service can be private or public, though many governments place restrictions on private systems.Since the mid-19th century, national postal systems have generally been established as government monopolies with a fee on the article prepaid.
Over the next hundred years the word mail began to be applied strictly to the letters themselves, and the sack as the mailbag. The term snail-mail is a retronym to distinguish it from the quicker email. Post is derived from Medieval French poste, which ultimately stems from the past participle of the Latin verb ponere ("to lay down or place").
The Mauryans developed early Indian mail service as well as public wells, rest houses, and other facilities for the common public.
Couriers were used militarily by kings and local rulers to deliver information through runners and other carriers.
Other sources claim much earlier dates for an Assyrian postal system, with credit given to Hammurabi (1700 BC) and Sargon II (722 BC).
Mail may not have been the primary mission of this postal service, however.