The letter-post classification encompasses all of the classes of international
mail: letters and letter packages, post and postal cards, aerogrammes,
printed matter, and small packets that were formerly categorized as LC
(letters and cards) and AO (other articles).
Any article that is otherwise acceptable and not prohibited by the country of
destination, subject to applicable weight and size limits, may also be mailed
at the letter-post rate, either airmail or economy.
The country-specific rate group designations that apply to airmail and
economy (surface) letter-post items, airmail and economy (surface) M-bags
(see 260), and books and sheet music (see 295) are as follows:
Rate Group 1
Rate Group 2
Rate Group 3
Rate Group 4
Rate Group 5
All other destination countries and territorial
possessions that are referenced in the
Individual Country Listings.
Note: See the Individual Country Listings for the airmail and economy
(surface) postage rates that are applicable to specific destination
countries and territorial possessions.
Mailers of letter-post items may pay postage with postage stamps, postage
meter stamps, postage validation imprinter (PVI) label, and by permit imprint.
243 Weight and Size Limits
243.1 Weight Limit
The weight limit is 4 pounds.
243.2 Size Limits
243.21 Envelopes and Packages
a. Minimum length and height: 5-1/2 x 3-1/2 inches.
b. Minimum depth (thickness): .007 inch.
c. Maximum length: 24 inches.
d. Maximum length, height, depth (thickness) combined: 36 inches.
a. Minimum length: 4 inches.
b. Minimum length plus twice the diameter combined: 6-3/4 inches.
c. Maximum length: 36 inches.
d. Maximum length plus twice the diameter combined: 42 inches.
Unenclosed cards exceeding the size limits for postcards are admissible at
the letter-post rate if they do not exceed 4-3/4 x 9-1/4 inches.
243.24 Nonmachinable Surcharge
A $0.13 per-piece surcharge is applied to an airmail letter-post item (but not
to an economy (surface) letter-post item) that weighs 1 ounce or less, if it has
one or more of the following characteristics:
a. Has any dimension that exceeds the acceptable standard dimension -
i.e., if length exceeds 11-1/2 inches, or if height exceeds 6-1/8 inches,
or if thickness exceeds 1/4 inch.
b. Has an aspect ratio (length divided by height) of less than 1.3 or more
c. Is polybagged, polywrapped, or enclosed in any plastic material.
d. Has clasps, strings, buttons, or similar closure devices.
e. Contains items such as pens, pencils, or loose keys or coins that cause
the thickness of the mailpiece to be uneven.
f. Is too rigid (does not bend easily when subjected to a transport belt
tension of 40 pounds around an 11-inch diameter turn).
g. For pieces more than 4-1/4 inches high or 6 inches long, the thickness
is less than 0.009 inch.
h. Has a delivery address parallel to the shorter dimension of the
i. For self-mailers with a folded edge perpendicular to the address, the
piece is not secured according to DMM 201.
j. For booklet-type pieces, the bound edge (spine) is the shorter
dimension of the piece or is at the top, regardless of the use of tabs,
wafer seals, or other fasteners.
244 Preparation Requirements
a. Letter-post items, which because of their size, shape, or configuration
might be mistaken for another class of international mail, should be
marked "LETTER" on the address side of the mailpiece.
b. Letter-post items that are paid for at the airmail rate of postage 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.
c. Mailpieces that are paid for at the economy (surface) rate of postage
for books and sheet music must be marked "BOOKS" or "SHEET
MUSIC," as applicable. See 295.41.
d. Economy (surface) 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.
e. Privately printed postcards must bear the marking "POSTCARD." See
Unregistered letter-post items may be sealed at the sender's option.
Registered items must be sealed. (See 334.4 for sealing
requirements for registered mail.)
The following packaging methods may be used when entering letter-post
a. Mail matter is admissible in envelopes, sleeves, or wrappers of varying
sizes and thickness. Note: Transparent plastic packaging is
acceptable for international mailing purposes.
b. Bulkier items are admissible in boxes, cartons, tubes, or other types of
containers that are commonly used to transmit shipments that are in
c. 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 as to prevent the mailpieces from
opening or being damaged during postal handling.
d. Letter-post items, in card form, are admissible, so long as their overall
dimensions do not exceed 4-3/4 X 9-1/4 inches. See 243.23.
244.5 Customs Forms Required
244.51 Dutiable Merchandise
a. 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
b. Letter-post items may contain dutiable merchandise unless the country
of destination prohibits dutiable merchandise in letters. (See Individual
c. When mailing articles that may be dutiable, sender must comply with
123.61 and with special instructions under "Customs Forms
Required" and "Observations" in Individual Country Listings.
244.52 Nondutiable Merchandise
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
Note: Because PS Form 2976 described in 123.61, generally
denotes dutiable contents, it should be omitted from letter-post mail when
the sender knows the contents are not dutiable, unless the item weighs
16 ounces or more.