Pub. L. 86-682, tit. 39, pt. IV, ch. 53, sec. 4054
Postage collection on Armed Forces mail
§ 4054. Postage collection on Armed Forces mail The Postmaster General may transmit, without the prepayment of postage, letters of members of the Armed Forces in the service of the United States certified in a manner prescribed by him, and collect the postage upon delivery.