24 CFR § 13.2 - Procedures for obtaining and disseminating data.
(a) HUD shall insert, manually and via automated inserts, pictures and biographical data related to missing children in domestic penalty mail directed to members of the public in the United States, its territories and possessions. These include:
(1) Standard letter-size envelopes (4 1/2″ × 9 1/2″);
(2) Document-size envelopes (9 1/2″ × 12″, 9 1/2″ × 11 1/2″, 10″ × 13″); and
(3) Other envelopes (miscellaneous size).
(b) Missing children information shall not be placed on the Penalty Indicia, OCR Read Area, Bar Code Read Area, and Return Address areas of letter-size envelopes.
(c) Posters containing pictures and biographical data shall be placed on bulletin boards in Headquarters and Field offices.
(d) HUD shall accept camera-ready and other photographic and biographical materials solely from the National Center for Missing and Exploited Children (National Center). Photographs that were reasonably current as of the time of the child's disappearance shall be the only acceptable form of visual media or pictorial likeness used in penalty mail or posters.