(1)
In general
For purposes of ensuring compliance with the Customs laws of the United States and other laws enforced by the Customs Service, including the provisions of law described in paragraph (2), a Customs officer may, subject to the provisions of this section, stop and search at the border, without a search warrant, mail of domestic origin transmitted for export by the United States Postal Service and foreign mail transiting the United States that is being imported or exported by the United States Postal Service.