39 U.S.C. § 3403
Matter for blind and other handicapped persons
(a)
The matter described in subsection (b) of this section (other than matter mailed under section 3404 of this title ) may be mailed free of postage, if—
(1)
the matter is for the use of the blind or other persons who cannot use or read conventionally printed material because of a physical impairment and who are certified by competent authority as unable to read normal reading material in accordance with the provisions of sections 135a and 135b of title 2;
(2)
no charge, or rental, subscription, or other fee, is required for such matter or a charge, or rental, subscription, or other fee is required for such matter not in excess of the cost thereof;
(3)
the matter may be opened by the Postal Service for inspection; and
(4)
the matter contains no advertising.
(b)
The free mailing privilege provided by subsection (a) of this section is extended to—
(1)
reading matter and musical scores;
(2)
sound reproductions;
(3)
paper, records, tapes, and other material for the production of reading matter, musical scores, or sound reproductions;
(4)
reproducers or parts thereof, for sound reproductions; and
(5)
braille writers, typewriters, educational or other materials or devices, or parts thereof, used for writing by, or specifically designed or adapted for use of, a blind person or a person having a physical impairment as described in subsection (a)(1) of this section.
( Pub. L. 91–375 , Aug. 12, 1970 , 84 Stat. 757 .)