7 CFR § 351.7 - Regulations governing importation by mail of plant material for immediate export.
To collectors of customs and others concerned:
(a) Shipments of plant material may be imported by mail free of duty for immediate exportation by mail subject to the following regulations, which have been approved by the Department of Agriculture and the Post Office Department:
(1) Each shipment shall be dispatched in the mails from abroad, accompanied by a yellow and green special mail tag bearing the serial number of the permit for entry for immediate exportation or immediate transportation and exportation, issued by the U.S. Department of Agriculture, and also the postal form of customs declaration.
(2) Upon arrival, the shipment shall be detained by, or redispatched to, the postmaster at Washington, DC, Brownsville, Tex., Hoboken, N.J., Honolulu, Hawaii, Jamaica, L.I., N.Y., Laredo, Tex., Miami, Fla., New Orleans, La., San Francisco, Calif., San Juan, P.R., San Pedro, Calif., or Seattle, Wash., as may be appropriate, according to the address on the yellow and green tag, and there submitted to the customs officer and the Federal quarantine inspector. The merchandise shall under no circumstances be permitted to enter the commerce of the United States.
(3) After inspection by the customs and quarantine officers, and with their approval, the addressee, or his authorized agent, shall repack and readdress the mail parcel under customs supervision; affix to the parcel the necessary postage, and comply with other mailing requirements, after which the parcel shall be delivered to the postmaster for exportation by mail pursuant to 19 CFR 9.11(a). The contents of the original parcel may be subdivided and exported in separate parcels in like manner.
(4) It will not be necessary to issue a customs mail entry nor to require formal entry of the shipments.
(5) The mail shipments referred to shall be accorded special handling only at the points specified in paragraph (a)(2) of this section.
(6) The foregoing procedure shall not affect the movement of plant material in the international mails in transit through the United States.