Quick search by citation:

39 U.S. Code § 1009 - Personnel not to receive fees

An officer or employee of the Postal Service may not receive any fee or perquisite from a patron of the Postal Service on account of the duties performed by virtue of his appointment, except as authorized by law.

(Pub. L. 91–375, Aug. 12, 1970, 84 Stat. 733.)
Statutory Notes and Related Subsidiaries
Effective Date

Section effective July 1, 1971, pursuant to Resolution No. 71–9 of the Board of Governors. See section 15(a) of Pub. L. 91–375, set out as a note preceding section 101 of this title.