- First-Class Mail International items must be marked “AIRMAIL/PAR AVION” or have PS Label 19–A, Par Avion Airmail, or PS Label 19–B, Par Avion Airmail, affixed to the address side of the mailpiece.
- First-Class Mail International packages (small packets) and rolls, which because of their size, shape, or configuration might be mistaken for another category of international mail, should be marked “LETTER-POST” on the address side of the mailpiece.
- First-Class Mail International items that qualify as matter for the blind must bear the marking “FREE MATTER FOR THE BLIND” in the upper–right corner of the address side of the mailpiece. See 274.2.
Unregistered First-Class Mail International items may be sealed at the sender’s option. Registered Mail items must be sealed. (See 334.4 for sealing requirements for Registered Mail service.)
The following packaging methods may be used when entering First-Class Mail International items:
- Mailers must package mailpieces to withstand normal transit and handling without content or package breakage, injury to USPS employees, or damage to other mail or USPS equipment.
- Mailers must package their contents to prevent their deterioration.
- Mail matter is admissible in envelopes, sleeves, or wrappers of varying sizes and thickness. Note: Transparent plastic packaging is acceptable for international mailing purposes.
- Bulkier items are admissible in boxes, cartons, tubes, or other types of containers that are commonly used to transmit shipments that are in package form.
- Except as provided in 292.4 and 293.4, folded mailpieces, without envelopes, are admissible provided that all of the open sides are secured with tape, tabs, or wafer seals of sufficient quantity and strength to prevent the mailpieces from opening or being damaged during postal handling.
- First-Class Mail International items, in card form, are permitted, so long as their overall dimensions do not exceed 4–3/4 inches or 9–1/4 inches. See 243.144.
- Any merchandise sent to another country may be subject to duty under the customs regulations of that country. The Postal Service does not maintain or provide information concerning the assessment of customs duty.
- First-Class Mail International items may contain dutiable merchandise unless the country of destination prohibits dutiable merchandise in letters. (See Individual Country Listings.)
- When mailing articles that may be dutiable, the sender must use PS Form 2976 or 2976-A as defined in 123.61 and must follow the special instructions under “Customs Forms Required” and “Observations” in the Individual Country Listings.
Nondutiable merchandise may be mailed (at the sender’s risk) to countries that do not accept dutiable merchandise. The Postal Service assumes no responsibility for the treatment such items may receive in the country of destination.
Note: Because PS Form 2976 described in 123.61 generally denotes dutiable contents, it should be omitted from First-Class Mail International items weighing less than 16 ounces when the contents are not dutiable.