ITAR - International Traffic in Arms Regulations 123.24: Handle U.S. Postal Service exports of hardware and technical data correctly

What does 123.24 require?

Hardware exported by U.S. mail under a licence or exemption must be filed with CBP before mailing and the package marked that the export is subject to the ITAR, citing the exemption or licence number and that export information was filed; technical data mailed under a licence must be notified electronically to DDTC and the package marked accordingly, with the licence returned to DDTC once used (123.24).