found an article tonight containing images of letters mailed with Confederate postage to Mail Route 1538 which was between Marianna and Campbellton. According to documents in the National Archives, my G-Great Grandfather, John Young Register of Geneva, had the contract to deliver the mail along this route in 1861. This was the road that the Yankees took before the Battle of Marianna.
http://www.jlkstamps.com/csa/archives/beau.htm