Notice of nondelivery of mail

§ 4106. Notice of nondelivery of mail (a) The Postmaster General may notify the sender or addressee when mail, other than mail of the first class, is undeliverable as addressed. (b) The Postmaster General shall notify the publisher or news agent when copies of a publication of the second class mailed by him are undeliverable as addressed. Copies of publications undeliverable as addressed received subsequent to the notice may be treated as directed by the Postmaster General.