(a) Mail article. “Mail article” means any posted parcel, packet, package, envelope, letter, aerogramme, box, card, or similar article or container, or any contents thereof, which is transmitted in mail subject to customs examination.

(b) Letter class mail. “Letter class mail” means any mail article, including packages, post cards, and aerogrammes, mailed at the letter rate or equivalent class or category of postage.

(c) Sealed letter class mail. “Sealed letter class mail” means letter class mail sealed against postal inspection by the sender.

(a) Restrictions. Customs examination of mail as provided in paragraph (b) of this section is subject to the restrictions and safeguards relating to the opening of letter class mail set forth in § 145.3.

(b) Generally. All mail arriving from outside the Customs territory of the United States which is to be delivered within the Customs territory of the United States and all mail arriving from outside the U.S. Virgin Islands which is to be delivered within the U.S. Virgin Islands, is subject to Customs examination, except:

(1) Mail known or believed to contain only official documents addressed to officials of the U.S. Government;

(2) Mail addressed to Ambassadors and Ministers (Chiefs of Diplomatic Missions) of foreign countries; and

(3) Letter class mail known or believed to contain only correspondence or documents addressed to diplomatic missions, consular posts, or the officers thereof, or to international organizations designated by the President as public international organizations pursuant to the International Organizations Act (see § 148.87(b) of this chapter). Mail, other than letter class mail, addressed to the designated international organizations is subject to Customs examination except where the organization certifies under its official seal that the mail contains no dutiable or prohibited articles. Any Customs examination made shall, upon request of the addressee international organization, take place in the presence of an appropriate representative of that organization.

(a) Matter in addition to correspondence. Except as provided in paragraph (e), Customs officers and employees may open and examine sealed letter class mail subject to Customs examination which appears to contain matter in addition to, or other than, correspondence, provided they have reasonable cause to suspect the presence of merchandise or contraband.

(b) Only correspondence. No Customs officer or employee shall open sealed letter class mail which appears to contain only correspondence unless prior to the opening:

(1) A search warrant authorizing that action has been obtained from an appropriate judge of United States magistrate, or

(2) The sender or the addressee has given written authorization for the opening.

(c) Reading of correspondence. No Customs officer or employee shall read, or authorize or allow any other person to read, any correspondence contained in any letter class mail, whether or not sealed, unless prior to the reading:

(1) A search warrant authorizing that action has been obtained from an appropriate judge or United States magistrate, or

(2) The sender or the addressee has given written authorization for the reading.

(d) Other types of correspondence. The provisions of paragraph (c) shall also apply to correspondence between school children and correspondence of the blind which are authorized to be mailed at other than the letter rate of postage in international mail.

(e) Certain Virgin Islands mail. First class mail originating in the Customs territory of the United States and arriving in the U.S. Virgin Islands, which is to be delivered within the U.S. Virgin Islands, shall not be opened unless:

(1) A search warrant authorizing that action has been obtained from an appropriate judge or United States magistrate, or

(2) The sender or the addressee has been given written authorization for the opening.

(a) Subject to seizure and forfeiture. When, upon CBP examination, a mail article is found to contain merchandise subject to duty or tax, and the mail article is not accompanied by an appropriate customs declaration and invoice or statement of value required by § 145.11, or is found to contain material prohibited importation or imported contrary to law, the merchandise is subject to seizure and forfeiture.

(b) Mitigation of forfeiture. Any claimant incurring a forfeiture of merchandise for violation of this section may file a petition for relief pursuant to part 171 of this chapter. Mitigation of that forfeiture may occur consistent with mitigation guidelines.

(c) Collection of mitigated forfeiture. When the shipment does not exceed $2,500 in value, CBP Form 3419 or 3419A or CBP Form 368 or 368A (serially numbered) or CBP Form 7501, or its electronic equivalent, must be used for the entry of the merchandise, and the duty, any tax, and the amount of the mitigated forfeiture must be entered as separate items thereon. If a mail article for which a mail fine entry has been issued in accordance with this paragraph is undeliverable, it will be returned to the director of the port where the entry was issued, for disposition in accordance with § 145.59 relating to articles subject to seizure.

(d) Petition for relief. The addressee or sender may file a petition with the Fines, Penalties, and Forfeitures Officer having jurisdiction over the port where the mail fine entry was issued in accordance with part 171 of this chapter for relief from the forfeiture incurred and for release of the seized merchandise, or for additional relief from a mitigated forfeiture.

Mail articles which are refused or undeliverable, except mail articles for which a mail fine entry has been issued in accordance with § 145.4(c), will be marked by the postmaster to show why delivery was not made, and will be forwarded to the proper exchange post office for return to the country of origin. Mail entries will be removed from the mail articles and returned to Customs for cancellation. If, for any reason, an undeliverable mail article known or supposed to be dutiable is not returned to the country of origin or forwarded to another country in accordance with the Postal regulations, it will be delivered to Customs for disposition under the Customs laws and regulations governing seized or unclaimed merchandise.