39 C.F.R. § 267.2
Consistent with the responsibility of the Postal Service to make its official records available to the public to the maximum extent required by the public interest, and to ensure the security, confidentiality, and integrity of official records containing sensitive or national security information, it is the policy of the Postal Service to maintain definitive and uniform information security safeguards. These safeguards will have as their purpose: (a) Ensuring the effective operation of the Postal Service through appropriate controls over critical information, and (b) Protecting personal privacy, the public interest, and the national security by limiting unauthorized access to both restricted and national security information.
39 C.F.R. §267.2