22 CFR 123.24: Shipments by U.S. Postal Service.

(a) The export of any defense hardware using a license or exemption in this subchapter by the U.S. Postal Service must be filed with U.S. Customs and Border Protection using its electronic system(s) and the license must be filed with U.S. Customs and Border Protection before any hardware is actually sent abroad by mail. The exporter must certify the defense hardware being exported in accordance with this subchapter by clearly marking on the package: “This export is subject to the controls of the ITAR, 22 CFR (identify section for an exemption) or (state license number) and the export has been electronically filed with U.S. Customs and Border Protection.”

(b) The export of any technical data using a license in this subchapter by the U.S. Postal Service must be notified electronically directly to the Directorate of Defense Trade Controls (DDTC). The exporter, using either a license or exemption, must certify, by clearly marking on the package, “This export is subject to the controls of the ITAR, 22 CFR (identify section for an exemption) or (state license number).” For those exports using a license, the exporter must also state “The export has been electronically notified directly to DDTC.” The license must be returned to DDTC upon completion of the use of the license (see § 123.22(c)).