Free transportation of postal officials

§ 6433. Free transportation of postal officials Every person engaged in the transportation of mail by vessel and, unless otherwise provided in the contract, every other contractor engaged in the transportation of mail shall carry on any vessel or vehicle he operates upon exhibiting their credentials and without extra charge therefor— (1) persons in charge of the mails when on duty and traveling to and from duty, and (2) accredited agents and officers, including postal inspectors, of the Department while traveling on official business.