Simply directing someone to the USPS site is not helpful.
The applicable USPS guidelines are
Pub 522
USPS Packaging Instruction 4B
https://pe.usps.com/text/pub52/pub52apxc_015.htm#ep1000053
Safety Matches
Safety matches (book, card, or strike–on–box) may be mailed only in domestic mail via surface transportation, provided all applicable requirements in 344 are met, including:
- They do not ignite spontaneously under conditions normally incident to transportation or when subjected for eight consecutive hours to a temperature of 200º F (93º C).
- They cannot be readily ignited by friction unless struck on their own or on a similar box, card, or book.
Note: Strike–anywhere matches assigned UN1331 and other types of matches assigned UN2254 or UN1945 are nonmailable.
Proper Shipping Name
ID Number
Mailability
- International Mail: Prohibited.
- Domestic Mail: Permitted only via surface transportation.
Required Packaging Primary Receptacle
- Mailable types of safety matches must be tightly packed in a securely sealed primary receptacle to prevent any shifting or movement that could cause accidental ignition by rubbing against adjoining items.
- Multiple primary receptacles are permitted per mailpiece.
Outer Packaging
- The outer packaging material must be made of fiberboard, wood, or other equivalent and be strong enough to prevent the inner contents from bursting through.
- The primary container(s) must be snugly packed within the outer packaging.
- Each mailpiece must not exceed a total weight of 25 pounds.
Marking
- The address side of each mailpiece must be clearly marked “Surface Only” or “Surface Mail Only” and either “Book Matches”, “Card matches,” or “Strike-on-Box Matches,” as applicable.
- A complete return address and delivery address must be used.
Documentation
- A shipping paper is not required.
