39 CFR § 211.2 - Regulations of the Postal Service.
(a) The regulations of the Postal Service consist of:
(1) The resolutions of the Governors and the Board of Governors of the U.S. Postal Service and the bylaws of the Board of Governors;
(2) The Mailing Standards of the United States Postal Service, Domestic Mail Manual; the Postal Operations Manual; the Administrative Support Manual; the Employee and Labor Relations Manual; the Financial Management Manual; the International Mail Manual; and those portions of Chapter 2 of the former Postal Service Manual and chapter 7 of the former Postal Manual retained in force.
(3) Headquarters Circulars, Management Instructions, Regional Instructions, handbooks, delegations of authority, and other regulatory issuances and directives of the Postal Service or the former Post Office Department. Any of the foregoing may be published in the Federal Register and the Code of Federal Regulations.
(b) Except as otherwise provided by law, the resolutions of the Governors and the Board of Governors of the U.S. Postal Service and the bylaws of the Board of Governors take precedence over all regulations issued by other authority.
(c) The adoption, by reference or otherwise, of any rule of law or regulation in this or any other regulation of the Postal Service shall not be interpreted as any expression on the issue of whether such rule of law or regulation would apply to the Postal Service if it were not adopted as a regulation, nor shall it restrict the authority of the Postal Service to amend or revoke the rule so adopted at a subsequent time.
(d) All regulations of the Post Office Department in effect at the time the U.S. Postal Service commenced operations, continue in effect, except as subsequently modified or repealed by the Postal Service. Except as otherwise continued in effect as postal regulations, all regulations of other agencies of the United States continued in effect as postal regulations by section 5(a) of the Postal Reorganization Act are repealed.