Nonmailable matter

§ 4001. Nonmailable matter (a) Matter, the deposit of which in the mails is punishable under sections 1302, 1341, 1342, 1461, 1463, 1714, 1715, 1716, 1717, or 1718 of title 18, is nonmailable. (b) Except as provided in section 4002 of this title, nonmailable matter which reaches the office of delivery, or which may be seized or detained for violation of law, shall be disposed of as the Postmaster General directs.