An Etymological Dictionary of the German Language/Post
Post, f., ‘post, post-office,’ first occurs in early ModHG., formed from Ital. posta (Fr. poste), which is based on MidLat. posita, ‘standing-place’ (for horses?). Similarly ModHG. Posten, ‘post, station, item, entry,’ is derived from Ital. posto, ‘place, post,’ which again comes from MidLat. positus, ‘standing-place.’