43 CFR 20.509 - Penalty mail and official stationery.
(a) An employee is prohibited from using any official envelope, label, or indorsement authorized by law, to avoid the payment of postage or registry fee on his or her private letter, packet, package, or other matter in the mail (18 U.S.C. 1719).
Title 43 published on 2013-10-01
no entries appear in the Federal Register after this date.