@peterdrake
The term "post-office"[3] has been in use since the 1650s,[4] shortly after the legalisation of private mail services in England in 1635.[5] In early modern England, post riders—mounted couriers—were placed, or "posted",[6]every few hours along post roads at posting houses (also known as post houses) between major cities, or "post towns". These stables or inns permitted important correspondence to travel without delay. In early America, post offices were also known as stations. This term, as well as the term "post house", fell from use as horse and coach services were replaced by railways, aircraft, and automobiles.
https://en.m.wikipedia.org/wiki/Post_office

@peterdrake

>"The post office implies the existence of a pre office."

And a now office. (or current office).