39 U.S.C. § 3204 - U.S. Code - Unannotated Title 39. Postal Service § 3204. Restrictions on use of penalty mail

(1) a request therefor has been previously received by the department or establishment; or

(2) its mailings is required by law.

(1) enclosures reasonably related to the subject matter of official correspondence;

(2) informational releases relating to the census of the United States and authorized by title 13;

(3) matter concerning the sale of Government securities;

(4) forms, blanks, and copies of statutes, rules, regulations, instructions, administrative orders, and interpretations necessary in the administration of the department or establishment;

(5) agricultural bulletins;

(6) lists of public documents offered for sale by the Superintendent of Documents;

(7) announcements of the publication of maps, atlases, and statistical and other reports offered for sale by the Federal Power Commission as authorized by section 825k of title 16; or

(8) articles or documents to educational institutions or public libraries, or to Federal, State, or other public authorities.