39 C.F.R. § 231.1 – Responsibility.

(a) The protection of mail, postal funds, and property is a responsibility of every postal employee.
(b) The Chief Postal Inspector is designated as the Security Officer for the U.S. Postal Service. That official is responsible for the issuance of instructions and regulations pertaining to security requirements within the Postal Service.
(39 U.S.C. 401)

[36 FR 4762, Mar. 12, 1971]