# Mailability: hazardous, restricted and perishable items

USPS refuses anything that may kill or injure someone or damage the mail, and accepts some hazardous, restricted and perishable items only under the conditions of its rulebook, [Publication 52](https://postalref.com/products/mailability.md).[^1][^2][^3] Permitted hazardous materials carry warning labels, the proper shipping name and the UN number on the address side, and hazardous materials codes in the barcode.[^4][^5]

Updated November 6, 2026. 102 sources.

## Questions

### How do I ship a laptop with a lithium battery through USPS?

A laptop with its lithium-ion battery installed can go by air or ground, if the battery is rated at 100 watt-hours or less.[^6][^7] A used laptop goes by ground only, marked `Restricted Electronic Device` and `Surface Transportation Only`.[^7][^8] A piece holds no more than eight cells or two batteries, and [lithium batteries](#batteries) gives the other limits.[^6]

### Can you send live animals in the mail?

Only some live animals are mailable, each under its own conditions, such as bees and day-old poultry.[^9] Warm-blooded pets such as cats, kittens, dogs and puppies are not mailable.[^9] Adult birds travel only by Priority Mail Express, and [perishable matter](#perishable) lists every kind that is mailable.[^9][^10]

### Why does USPS ask about lithium batteries, and does it charge extra?

USPS retail clerks must ask whether a package holds anything potentially hazardous, such as lithium batteries, to set the limits, labels and packaging it needs.[^11] As of July 12, 2026, Priority Mail Express and Priority Mail parcels with hazardous materials, lithium batteries included, pay a $7.50 HazMat Handling Fee.[^12][^13] USPS Ground Advantage and Parcel Select parcels pay $0.00, as [marking and codes](#marking) explains.[^12]

### How do I mail cremated remains through USPS, and how much does it cost?

Within the United States, cremated remains go only by Priority Mail Express, in a strong, sealed, sift-proof receptacle inside USPS's own [cremated remains box](#restricted), `BOX-CRE`.[^14][^15] Priority Mail Express postage goes by weight and zone: as of October 4, 2026, a retail piece up to 0.5 pound costs from $37.05.[^16][^17] Additional insurance and Return Receipt, the only [extra services](https://postalref.com/guides/extra-services.md) allowed, are charged on top of the postage.[^14][^18]

### What is considered hazardous material for shipping?

A hazardous material is any article or substance the U.S. Department of Transportation designates as able to pose unreasonable risks to health, safety or property in transportation.[^19] Each one belongs to one of nine hazard classes, such as explosives, gases or flammable liquids.[^20] Each is mailable, mailable with restrictions, or prohibited, as [hazardous materials](#hazardous) explains.[^19]

### Does USPS ship lithium batteries internationally?

Only lithium batteries installed in the equipment they operate may go abroad, at most four cells or two batteries a shipment.[^21] The piece must not show any mark or label that says it holds lithium batteries.[^21] Used, damaged, defective or recalled batteries, and used or damaged devices that hold them, never go abroad.[^21]

### Can you mail dry ice with USPS?

Yes, within the United States: a piece may hold up to 5 pounds of dry ice by air, and more by surface.[^22][^23] The package must be vented and marked with what the dry ice cools, the dry ice's net weight and `Dry Ice, UN1845`, as [dry ice](#batteries) explains.[^24][^23] International mail takes no dry ice.[^22]

### Can you mail alcohol with USPS?

No: USPS does not accept intoxicating liquors, taxable beverages with 0.5 percent or more alcohol by weight, even by prescription or as a collector's item.[^25][^26] Cooking wine, mouthwash and other alcohol products are mailable if they meet IRS and FDA rules and are not taxable beverages, poisonous or flammable.[^25] Federal and state agency employees may mail liquor to each other for official use, as [restricted matter](#restricted) explains.[^25] International mail prohibits intoxicating liquor too, as it does all matter that is nonmailable at home.[^27]

## How it fits together

Federal law makes all matter that is dangerous to life, health or property nonmailable, and USPS's mailability rules start from that premise.[^28][^1] Publication 52, [Hazardous, Restricted, and Perishable Mail](https://postalref.com/products/mailability.md), sets the conditions under which some of that matter is still accepted.[^2][^3] It sorts the matter into three kinds: hazardous materials, restricted matter and perishable matter.[^29] Each kind holds items that are mailable, mailable with restrictions, or prohibited.[^19][^30][^31]

Hazardous materials fall into nine hazard classes, and USPS generally takes only retail-sized consumer quantities of them.[^20][^32] Their rules depend on how a piece travels: Priority Mail Express and Priority Mail meet air rules, and USPS Ground Advantage meets surface rules.[^33][^34][^35] Lithium batteries and dry ice are hazardous materials with limits of their own.[^13] A permitted piece carries its labels on the address side and hazardous materials codes in its barcode, which [package labels](https://postalref.com/guides/package-labels.md) also covers.[^4][^5]

Restricted matter is matter that federal law limits, such as liquor, firearms, sharp objects and tobacco.[^30][^29] Perishable matter, such as live animals, food and plants, can spoil in the mail and goes at the mailer's own risk.[^31] A handling fee, one of the [extra services](https://postalref.com/guides/extra-services.md), also applies to live animals and perishable items.[^31]

International mail is stricter: almost all dangerous goods are prohibited, and matter nonmailable at home is prohibited abroad too.[^36][^27] When mailability is uncertain, the mailer can ask the PCSC, USPS's [Pricing and Classification Service Center](https://postalref.com/products/pricing-and-classifications-service-center.md), for a ruling.[^37][^28] Product Classification, an office at USPS Headquarters, also takes these requests and decides appeals of the PCSC's rulings.[^37]

## Hazardous materials

A hazardous material is an article or substance that the U.S. Department of Transportation, DOT, designates as able to pose unreasonable risks in transportation.[^19] In international commerce it is called dangerous goods.[^38] DOT regulates its carriage under 49 CFR, and USPS rules follow 49 CFR with more limits and prohibitions of their own.[^19]

DOT assigns every hazardous material to one of nine hazard classes:[^20]

- Class 1, explosives.[^20]
- Class 2, gases.[^20]
- Class 3, flammable and combustible liquids.[^20]
- Class 4, flammable solids.[^20]
- Class 5, oxidizing substances and organic peroxides.[^20]
- Class 6, toxic substances and infectious substances.[^20]
- Class 7, radioactive materials.[^20]
- Class 8, corrosives.[^20]
- Class 9, miscellaneous hazardous materials, such as lithium batteries and dry ice.[^20][^13]

Domestic mail generally takes only materials DOT allows as a Limited Quantity, sold in retail form and meant for personal care or household use.[^32] Such a material is a consumer commodity.[^39] The hazardous materials table in Appendix A shows whether each material is mailable by air and by surface, found by its proper shipping name.[^20] To get a mailability decision, the mailer gives the Post Office a Safety Data Sheet and details about the material.[^37]

The mode of transportation decides the rules.[^33] Anything sent as Priority Mail Express or Priority Mail must meet the air rules, however it actually travels.[^34] These are always prohibited by air:[^34]

- Explosives.[^40]
- Flammable gases, liquids and solids.[^34]
- Radioactive materials.[^34]
- Lithium batteries without their equipment.[^34][^7]

Four provisions let small amounts travel with fewer DOT requirements:

- Limited Quantity surface material presents a limited hazard by its form, quantity and packaging, and never goes by Priority Mail Express or Priority Mail.[^41]
- ID8000 material is a consumer commodity of Class 2, 3 or Division 6.1 that may go by air.[^39]
- An excepted quantity may go by domestic air or surface, at most 30 g or 30 ml in each inner packaging.[^41][^42]
- A small quantity may go only by domestic highway and rail.[^42]

An aerosol is a nonrefillable metal can of gas under pressure that sprays out a liquid, paste or powder.[^43] The hazardous materials table lists flammable aerosols as Division 2.1, flammable gases, and nonflammable ones as Division 2.2.[^44] By domestic air, flammable gases are prohibited, and nonflammable gases generally go when they qualify as ID8000 material.[^45] By domestic surface, both generally go as Limited Quantity material, within quantity and packaging limits.[^45] International mail takes no gases.[^45]

Aerosol paint that counts as a flammable compressed gas goes by surface only, as Limited Quantity material.[^46] Flammable liquids, such as rubbing alcohol, are prohibited by air.[^47][^48] A liquid's flashpoint is the lowest temperature at which it gives off enough vapor to form an ignitable mixture with air.[^49] By surface, flammable liquids with a flashpoint at or below 20° F (-7° C) are prohibited too.[^48] The others go by surface only as Limited Quantity material that meets Exhibit 343.21.[^48]

Some hazardous materials need USPS approval before the first mailing, and the product page explains each:

- [Toy propellant devices](https://postalref.com/products/mailability.md#toy-propellant-devices), a mailable explosive, by surface once Product Classification approves them.[^40]
- [Safety fuses](https://postalref.com/products/mailability.md#safety-fuse), the only other mailable explosive, by surface under the same approval.[^40]
- [Lighters](https://postalref.com/products/mailability.md#lighters), with an approval letter from the PCSC director.[^50]
- [Ethanol-based flammable liquids and solids](https://postalref.com/products/mailability.md#ethanol-based-flammable-liquids-solids), by domestic air with prior written authorization.[^50]
- [Sharps and regulated medical waste](https://postalref.com/products/mailability.md#sharps-and-regulated-medical-waste), in container systems whose vendors USPS authorizes.[^51]

[Category B infectious substances](https://postalref.com/products/mailability.md#category-b-infectious-substances) go within the United States only for medical or veterinary use, research, or public health laboratory certification.[^52] They travel in triple packaging, by Priority Mail or Priority Mail Express.[^53] To go abroad, they also need written approval from the director of Product Classification.[^52]

> Mailers must identify whether a shipment contains hazardous materials when generating the label, including Postal Service-generated labels (e.g., from USPS Application Programming Interfaces (API), Click-N-Ship, or Merchant Returns Application).[^5]

**Must.** A mailer must say whether a shipment holds hazardous materials when making its label, including labels made with USPS's own tools.

- **hazard class**: “Hazard class means the category to which a hazardous material is assigned under the definitions set by DOT in 49 CFR.”[^49]
- **Limited Quantity**: “Limited Quantity is the maximum amount of a specific hazardous material that is exempted from the labeling or packaging requirements in 49 CFR.”[^54]
- **consumer commodity**: “A hazardous material that is packaged and distributed in a quantity and form intended or suitable for retail sale and designed for consumption by individuals for their personal care or household use purposes. This term can include certain drugs or medicines. Not all hazardous material permitted to be mailed as a limited quantity can qualify as a consumer commodity.”[^55]
- **ID8000**: “Certain hazardous materials in Classes 2 and 3 and Division 6.1 may qualify as consumer commodity subject to the applicable 49 CFR requirements and are reclassed as ID8000 when authorized to be carried on passenger aircraft.”[^39]
- **excepted quantity**: “An excepted quantity refers to a defined amount of a specific hazardous material that is eligible for transport aboard passenger aircraft and is exempt from most DOT requirements (e.g., packaging, marking, labeling) under 49 CFR § 173.4a.”[^41]
- **small quantity**: “Small quantity is the maximum amount of a specific hazardous material that is not subject to any requirements other than those in 49 CFR § 173.4.”[^35]
- **Safety Data Sheet**, also called SDS, MSDS, Material Safety Data Sheet: “Safety Data Sheet (SDS) is a document that details the physical characteristics and health hazards of a chemical or hazardous product.”[^56]
- **Hazardous Materials**, also called HAZMAT, Dangerous goods: “Any article or substance designated by the U.S. Department of Transportation (DOT) as being capable of posing an unreasonable risk to health, safety, and property during transportation. Not all hazardous materials are mailable, and those that are mailable must be prepared, documented, and marked according to specific requirements.”[^57]

## Lithium batteries and dry ice

Lithium batteries and dry ice are Class 9 hazardous materials, mailable within limits that depend on how a piece travels.[^13] A lithium-ion battery is rechargeable, as in phones and laptops.[^13] A lithium metal battery is not, and it often powers cameras and flashlights.[^58]

Every cell or battery must meet the UN Manual of Tests and Criteria, and the outer packaging must be rigid.[^8] Batteries go by air only in or with the equipment they run:[^7]

| Battery | In or with its equipment | Without equipment |
| --- | --- | --- |
| Lithium-ion | Air or surface; each cell up to 20 Wh, each battery up to 100 Wh[^6] | Surface only, in its sealed packaging, in a piece of up to 5 pounds[^59] |
| Lithium metal | Air or surface; each cell up to 1.0 gram of lithium, each battery up to 2.0 grams[^60] | Surface only, in its sealed packaging, in a piece of up to 5 pounds[^60][^6] |

With equipment, a piece holds no more than eight cells or two batteries.[^6] Very small batteries, up to 2.7 Wh or 0.3 grams of lithium, have no count limit in a piece of up to 5.5 pounds.[^6][^60] Used, damaged or defective devices go by surface only, marked `Restricted Electronic Device` and `Surface Transportation Only`.[^7][^8] Damaged, defective or recalled batteries are prohibited, unless the director of Product Classification approves them.[^24]

The DOT lithium battery mark goes flat on the address side, never folded over two sides.[^8] It shows the UN number for the battery and how it is packed:

| Proper shipping name | UN number |
| --- | --- |
| Lithium-ion battery | `UN3480`[^7] |
| Lithium-ion battery contained in or packed with equipment | `UN3481`[^61] |
| Lithium metal battery | `UN3090`[^61] |
| Lithium metal battery contained in or packed with equipment | `UN3091`[^61] |

A piece with no more than four cells or two batteries installed in the equipment they run needs no mark.[^8] A piece of loose batteries also says that it goes by surface only and is forbidden aboard passenger aircraft.[^59][^6]

Dry ice is solid carbon dioxide, used mainly to keep other items cool, such as medical specimens or foods.[^24] As it turns to gas it can displace oxygen, and in a closed container its pressure can make the container burst.[^24] A package with dry ice must be vented, and a piece sent by air holds at most 5 pounds.[^24][^22] Dry ice is prohibited in international mail.[^22]

Every piece with dry ice is marked on the address side with what the dry ice cools and the dry ice's net weight.[^23] By air, the piece carries a Class 9 warning label and the mark `Dry Ice, UN1845`.[^23] It also needs a Shipper's Declaration for Dangerous Goods, the shipping paper for air, fixed to its outside in triplicate.[^62][^33] By surface, the piece is marked `Surface Only` and `Dry Ice, UN1845`, needs no declaration or Class 9 label, and may hold more than 5 pounds.[^23][^62]

- **lithium battery**: “Lithium battery: A unit composed of one or more lithium cells which are electrically connected together by a permanent means, including case, terminals, and markings.”[^58]
- **lithium-ion battery**, also called Lithium-Ion Cell or Battery, secondary lithium cells or batteries: “Lithium-Ion Cell or Battery: A rechargeable electrochemical cell or battery in which the positive and negative electrodes are both lithium compounds constructed with no metallic lithium in either electrode.”[^13]
- **lithium metal battery**, also called Lithium Metal Cell or Battery, primary lithium cells or batteries: “Lithium Metal Cell or Battery: A non-rechargeable electrochemical cell or battery utilizing lithium metal or lithium alloys as the anode.”[^13]
- **dry ice**, also called carbon dioxide solid: “Dry ice (carbon dioxide solid) is produced by expanding liquid carbon dioxide to vapor and compacting the material into blocks.”[^24]

## Marking and codes

A package of hazardous materials must show the DOT warning labels and markings that 49 CFR 172.407 through 172.446 set out.[^63] Only the warning labels in Exhibits 325.4a, 325.4b and 325.5 of Publication 52 are permitted in USPS networks.[^63][^3] The sizes and colors of the labels those exhibits show are for reference only, and they don't meet DOT's standards unless an exhibit notes otherwise.[^63]

Every hazardous materials label and marking goes on the address side, with the proper shipping name and the UN number.[^4] Labels may go on an adjacent side when space runs out, but never on the bottom.[^4] A UN number is the four-digit number the United Nations assigns to a hazardous material.[^35] DOT warning labels are diamonds at least 100 mm on each side.[^4]

A Limited Quantity mark is a diamond with a black top and bottom.[^64] For air it has a black `Y` in the center, and the piece also shows the proper shipping name and identification number.[^64] For surface, the mark alone is enough.[^64]

Most mailable hazardous materials sent by air need shipping documentation, and some sent by surface need it too.[^33] For air it is a Shipper's Declaration for Dangerous Goods, and for surface a shipping paper.[^33] The mailer signs it in triplicate and fixes it to the outside of the piece in an envelope that opens easily.[^33]

In the barcode, a hazardous materials package carries a service type code of its own, which names the product and marks the contents as hazardous.[^5] Every such package also carries an extra service code for hazardous material, and USPS strongly recommends a second code for its category.[^65][^3] The label shows an `H` service icon in its upper left corner.[^66] Pieces to military addresses or to U.S. Possessions, Territories, and Freely Associated States use no hazardous materials service type code and no `H` icon, and they follow international rules.[^3]

> Mailers tendering packages that contain hazardous materials to the Postal Service must use Extra Service Code (ESC) 857.[^5]

**Must.** Every package that holds hazardous materials must carry extra service code `857`.

The extra service code for any hazardous material, then one code for each category.

| Code | Extra service |
| --- | --- |
| `810` | HAZMAT Air Eligible Ethanol Package |
| `811` | HAZMAT Class 1 - Toy Propellant/Safety Fuse Package |
| `812` | HAZMAT Class 3 – Flammable Liquid Package |
| `813` | HAZMAT Class 7 - Radioactive Materials Package |
| `814` | HAZMAT Class 8 - Corrosive Materials Package |
| `815` | HAZMAT Class 8 - Nonspillable Wet Battery Package |
| `816` | HAZMAT Class 9 - Lithium Battery Marked - Ground Only Package |
| `817` | HAZMAT Class 9 - Lithium Battery - Returns Package |
| `818` | HAZMAT Class 9 - Lithium batteries, marked package |
| `819` | HAZMAT Class 9 - Dry Ice Package |
| `820` | HAZMAT Class 9 - Lithium batteries, unmarked package |
| `821` | HAZMAT Class 9 - Magnetized Materials Package |
| `822` | HAZMAT Division 4.1 – Flammable Solids or Safety Matches Package |
| `823` | HAZMAT Division 5.1 - Oxidizers Package |
| `824` | HAZMAT Division 5.2 - Organic Peroxides Package |
| `825` | HAZMAT Division 6.1 – Toxic Materials Package |
| `826` | HAZMAT Division 6.2 – Infectious Substances Package |
| `827` | HAZMAT Excepted Quantity Provision Package |
| `828` | HAZMAT Ground Only |
| `829` | HAZMAT ID8000 Consumer Commodity Package |
| `830` | HAZMAT Lighters Package |
| `831` | HAZMAT LTD QTY Ground Package |
| `832` | HAZMAT Small Quantity Provision Package |
| `857` | Hazardous Material |

24 codes in the Extra Service Codes, Pub 199 Appendix J Table 7, where Code is 857 or 810 or 811 or 812 or 813 or 814 or 815 or 816 or 817 or 818 or 819 or 820 or 821 or 822 or 823 or 824 or 825 or 826 or 827 or 828 or 829 or 830 or 831 or 832.

One hazardous materials service type code, for Priority Mail with USPS Tracking.

### IMpb Service Type Code List `116`

- Description: Priority Mail USPS Tracking Hazardous Materials
- Mail class: PM
- Banner text: USPS TRACKING # HAZMAT
- Extra service codes: 920, 857

IMpb Service Type Code List, Appendix I.[^67]

A surface piece with hazardous materials carries the endorsement `Address Service Requested`, `Forwarding Service Requested` or `Return Service Requested`, which [undeliverable mail](https://postalref.com/guides/undeliverable-mail.md) explains.[^4][^68] `Change Service Requested` is not permitted on it.[^69]

As of July 12, 2026, a Priority Mail Express or Priority Mail parcel that holds hazardous materials pays a $7.50 HazMat Handling Fee.[^12] A USPS Ground Advantage or Parcel Select parcel that holds them pays $0.00.[^12] A commercial parcel whose hazardous materials USPS detects but the mailer did not declare or label pays a $50.00 HazMat Noncompliance Fee.[^12]

Mailing a hazardous material.

1. The mailer identifies the material's hazardous properties, such as flashpoint and toxicity.[^5]
2. The mailer finds its proper shipping name in Appendix A to learn its mailability.[^20]
3. The mailer packs it by the Packaging Instruction in Appendix C for its mode.[^34]
4. The mailer puts every required label and mark on the address side.[^4]
5. The mailer declares the hazardous material when making the label.[^5]
6. The mailer presents hazardous materials pieces apart from other mail, in containers marked `HAZMAT`.[^20]

- **Hazmat Extra Service Codes**, also called content-specific ESC, category-specific ESCs: “The Postal Service has also defined Extra Service Codes (ESCs) to identify the category of hazardous material that is associated with specific quantity restrictions, packaging and markings requirements, and for some ESCs, restrictions in air transportation.”[^3]
- **proper shipping name**: “Proper shipping name is the name of a hazardous material that must be used to identify a substance or article in the shipping documents and on the packaging, as required.”[^70]
- **Shipper's Declaration for Dangerous Goods**: “Shipping papers are referred to as a Shipper's Declaration for Dangerous Goods when being offered for air transportation according to the Dangerous Goods Regulations of the International Air Transport Association (IATA).”[^33]
- **Service Type Code**, also called STC: “Service Type Codes are designators used to represent USPS classes of mail in conjunction with the type of Extra Service(s) being requested.”[^71]
- **UN Number**: “The United Nations (UN) four-digit identification number assigned to a hazardous material that is recognized for use in international and domestic commerce and transportation.”[^35]
- **shipping paper**: “Domestically, a shipping paper means a shipping order, bill of lading, waybill, or manifest, per 49 CFR § 171.8, which identifies hazardous materials being offered for surface transportation.”[^33]

## Restricted matter

Restricted matter is matter whose mailing federal law generally restricts.[^30] The mailer must meet USPS rules and every federal, state and local law on shipping it.[^30] A doubtful item can go to the local postmaster for a ruling.[^30]

| Item | In domestic mail |
| --- | --- |
| Intoxicating liquors | Nonmailable, even by prescription or as a collector's item; exempt only between federal or state agency employees for official use[^26][^25] |
| Handguns | Nonmailable, except between licensed manufacturers, dealers and importers, or to listed officials for official duties after an affidavit[^72][^73][^74] |
| Unloaded rifles and shotguns | Mailable under federal, state and local law[^75] |
| Switchblade knives | Mailable only to government supply or procurement officials, and by makers and dealers to them[^76] |
| Other knives and sharp instruments | Mailable in a strong container, cushioned so edges cannot cut through[^77] |
| Cigarettes, smokeless tobacco and electronic nicotine delivery systems | Generally nonmailable, unless an exception applies[^78] |
| Cremated remains | Priority Mail Express only, in USPS's `BOX-CRE` box[^14] |
| Nonhazardous liquids and powders | Mailable when packed leakproof or sift-proof[^77] |
| Matter with an obnoxious odor | Nonmailable[^77] |

Regulated firearms travel with tracking and a signature at delivery, unless they go between licensed dealers, manufacturers or importers.[^72] USPS may require the mailer to open the package, or certify in writing that the weapon is unloaded and not concealable.[^72] Licensed makers, dealers and importers who mail handguns file PS Form 1508, Statement by Shipper of Firearms, with the postmaster.[^73] Postmasters give no opinion on whether a firearm shipment is legal, and they refer mailers to ATF.[^79] Small arms ammunition is prohibited from mailing.[^80]

A package with a mailable firearm must carry no mark on its outside wrapper or container that says what it holds.[^72]

Cremated remains in any form, such as ashes, keepsakes or jewelry, go within the United States only by Priority Mail Express.[^16] Abroad, they go only by Priority Mail Express International, and only where the destination country permits them.[^14] Every cremated remains mailing uses USPS's own `BOX-CRE` box.[^15]

The receptacle that holds the remains must be strong, durable and sealed so that it is sift-proof.[^15] Abroad, it must be a funeral urn, sealed and sift-proof.[^15] The mailer seals the receptacle in a plastic bag, places it in the box, and pads the bottom, sides and top so nothing moves.[^15] USPS recommends a slip on the bag with both addresses and the words `Cremated Remains`, in case the label comes off.[^15][^81]

[Cigarettes, smokeless tobacco and electronic nicotine delivery systems](https://postalref.com/products/mailability.md#cigarettes-smokeless-tobacco-and-ends) have narrow exceptions, for example between licensed businesses.[^82] [Drug mail-back programs](https://postalref.com/products/mailability.md#drug-mailback-program) let authorized DEA registrants receive unused drugs for disposal.[^83]

Publication 52 covers articles and substances, and the Domestic Mail Manual covers nonmailable written, printed and graphic matter.[^3][^84] That matter includes certain solicitations, lottery matter and some advertising.[^85] The addressee of a pandering advertisement can ask USPS for a prohibitory order, which directs the sender to make no further mailing to that addressee.[^86] The PCSC handles these orders.[^87]

- **intoxicating liquors**, also called alcoholic beverages: “Intoxicating liquors are beverages with an alcohol content of 0.5 percent or more by weight and are taxable per Chapter 51 of the United States (U.S.) Internal Revenue Service (IRS) Code.”[^25]
- **firearm**: “Firearm: Any device, including a starter gun, which will, or is designed to, or may readily be converted to, expel a projectile by the action of an explosive; the frame or receiver of any such weapon; any firearm muffler or firearm silencer; or any destructive device; but the term shall not include antique firearms (except antique firearms meeting the description of a handgun or of a firearm capable of being concealed on a person).”[^26]
- **handgun**: “Handgun (Including Pistols and Revolvers): A firearm with a short stock designed to be held and fired by the use of a single hand and subject to 431.1, or a combination of parts from which a handgun can be assembled.”[^26]
- **sharp instruments**: “Sharp instruments include all sharp-pointed or sharp-edged implements, such as knives, tools, ice picks, razor blades, stilettos, or similar devices.”[^76]
- **switchblade knife**: “A switchblade knife features a blade that opens automatically by hand pressure applied to a button or other device on the handle, or through inertia, gravity, or both.”[^76]
- **prohibitory order**: “A USPS order requested by the addressee of a pandering advertisement that directs the sender to make no further mailing to that addressee.”[^86]
- **nonmailable written, printed, and graphic matter**: “Matter that would be otherwise mailable that includes certain solicitations, lottery and certain advertising matter, and matter using any fictitious name, title, or address in conducting any scheme or device in violation of law. The solicitations may be either in guise of bills, invoices, or statements of account, or they may deceptively imply federal connection, approval, or endorsement.”[^85]
- **restricted matter**: “Any item on which certain mailing restrictions have been imposed for legal reasons other than risk of harm to persons or property involved in moving the mail and that require specific endorsements and markings. Examples include intoxicating liquors, abortive or contraceptive devices, odd-shaped items in envelopes, motor vehicle master keys, locksmithing devices as well as odor-producing materials, certain liquids and powders, battery-powered devices, and certain tobacco products.”[^88]

## Perishable matter and live animals

Perishable matter is anything that can deteriorate in the mail and so lose value, create a health hazard, or cause an odor or nuisance.[^29] It goes at the mailer's own risk, packaged as required and deliverable before it spoils.[^31] The Live Animal and Perishable Handling Fee applies to live animals and perishable items, such as fruit and meat.[^31] It applies to Priority Mail Express, Priority Mail and USPS Ground Advantage.[^31]

These live animals are mailable, each under its own conditions:[^9]

- Honeybees, by surface only, and queen honeybees, by air or surface.[^89]
- Day-old poultry, no more than 24 hours old, in the hatchery's original, unopened box.[^90]
- [Adult birds](https://postalref.com/products/mailability.md#adult-birds), by Priority Mail Express only, in a container Product Classification approved.[^10][^91]
- Scorpions, only for medical research or the manufacture of antivenin.[^92]
- Small, harmless cold-blooded animals, except snakes, turtles and turtle eggs.[^92]

Other warm-blooded animals are not mailable.[^9] Snakes, turtles and poisonous reptiles are not mailable either, and neither are poisonous insects or any spider.[^9] A live animal container is at least 275-pound test, double-wall fiberboard, and USPS packaging such as Flat Rate boxes cannot be used.[^93]

> Each mailpiece must display a complete return address and be marked on the address side with a description of the contents (e.g., "Live Animals," "Live Honeybees").[^94]

**Must.** A piece with live animals must show a complete return address and must name its contents on the address side.

Fresh fruits and vegetables are mailable only when dry, and other foods that spoil before they arrive are not mailable.[^95] Meat goes only under U.S. Department of Agriculture rules, and eggs only when each one is cushioned.[^96] Dry ice that keeps meat cold follows the [dry ice](#batteries) rules.[^96] Plants are mailable within the United States, but a quarantine can make a plant nonmailable from its area.[^96]

## International mail

Almost all dangerous goods are prohibited in international mail.[^36] Only biological substances, limited amounts of radioactive material, certain magnetized materials and lithium batteries installed in equipment can go, under specific circumstances.[^97] Countries add their own limits, so the mailer checks the destination's Individual Country Listing in the International Mail Manual.[^98]

Shipments to U.S. Possessions, Territories, and Freely Associated States follow the international rules for dangerous goods, because they are outside the U.S. customs territory.[^36] International dangerous goods shipments carry extra service code `857` and the code for their category.[^97]

Matter that is nonmailable at home, such as intoxicating liquor, is also prohibited abroad.[^27] The domestic firearms rules apply abroad too, and many firearms are prohibited.[^99] Most live or dead animals are nonmailable in international mail.[^100]

## What goes wrong

- A reused box that still shows hazardous materials or alcohol markings is treated as holding those contents.[^101] USPS employees cannot remove the marks, even when the mailer asks.[^101]
- Surface labels on Priority Mail Express or Priority Mail, used to keep a piece off aircraft, are prohibited.[^41]
- Combining several extra services on a package of hazardous materials, such as Signature Confirmation with insurance, is prohibited.[^5]
- A package of hazardous materials that misses any compliance element can draw the Hazmat Quality fee, as [package payment](https://postalref.com/guides/package-payment.md) explains.[^102]
- Live animals marked `If Undeliverable, Abandon` are not eligible for mailing.[^94]
- Live animals that cannot be delivered or returned within the delivery period marked on the package are disposed of.[^94]
- Anyone who knowingly mails dangerous matter may owe a civil penalty per violation, cleanup costs and criminal penalties, as [the product page](https://postalref.com/products/mailability.md#problems) explains.[^2]

## Index: 23 entries

### Extra service (1)

- [Hazmat Extra Service Codes](https://postalref.com/guides/mailability.md#marking)

### Program (1)

- [Drug Mailback Program](https://postalref.com/products/mailability.md#drug-mailback-program)

### File (1)

- [shipping paper](https://postalref.com/guides/mailability.md#marking)

### Documents (2)

- [Publication 52](https://postalref.com/products/mailability.md#terms)
- [USPS Container Requirements for Adult Birds](https://postalref.com/products/mailability.md#adult-birds)

### Terms (18)

- [aerosol](https://postalref.com/?q=aerosol)
- [Category B Infectious Substances](https://postalref.com/products/mailability.md#category-b-infectious-substances)
- [Cigarettes, Smokeless Tobacco, and Electronic Nicotine Delivery Systems](https://postalref.com/products/mailability.md#cigarettes-smokeless-tobacco-and-ends)
- [Electronic Nicotine Delivery System](https://postalref.com/products/mailability.md#terms)
- [Ethanol-based Flammable Liquids and Solids](https://postalref.com/products/mailability.md#ethanol-based-flammable-liquids-solids)
- [Hazardous Materials](https://postalref.com/guides/mailability.md#hazardous)
- [infectious substance](https://postalref.com/products/mailability.md#terms)
- [Lighters](https://postalref.com/products/mailability.md#lighters)
- [mailability](https://postalref.com/products/mailability.md)
- [nonmailable articles and substances](https://postalref.com/products/mailability.md#terms)
- [perishable matter](https://postalref.com/products/mailability.md#terms)
- [prohibitory order](https://postalref.com/guides/mailability.md#restricted)
- [restricted matter](https://postalref.com/guides/mailability.md#restricted)
- [Safety Fuse](https://postalref.com/products/mailability.md#safety-fuse)
- [Sharps and Regulated Medical Waste](https://postalref.com/products/mailability.md#sharps-and-regulated-medical-waste)
- [Toy Propellant Devices](https://postalref.com/products/mailability.md#toy-propellant-devices)
- [U.S. Possessions, Territories, and Freely Associated States](https://postalref.com/?q=U.S.%20Possessions%2C%20Territories%2C%20and%20Freely%20Associated%20States)
- [UN Number](https://postalref.com/guides/mailability.md#marking)

## Sources

[^1]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=18), PDF page 18: “The basic premise of the Postal Service mailability statutes is that anything which may kill or injure another or injure the mail or other property is nonmailable.”

[^2]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=16), PDF page 16: “Certain hazardous materials and otherwise restricted and perishable matter may be mailed under the conditions permitted within this publication. … If you knowingly mail items or materials that are dangerous or injurious to life, health, or property or fail to follow Postal laws on mailing hazardous materials in violation of 39 U.S.C § 3018 and 18 U.S.C. § 1716, you may be liable for: … A civil penalty per violation; refer to 39 CFR § 233.12 for values. … Cost of any cleanup associated with each violation. … Criminal penalties.”

[^3]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=125), page 126: “Publication 52, Hazardous, Restricted, and Perishable Mail, provides important information to help mailers determine what may be mailed and how certain items must be packaged to keep the mail safe. … The Postal Service has also defined Extra Service Codes (ESCs) to identify the category of hazardous material that is associated with specific quantity restrictions, packaging and markings requirements, and for some ESCs, restrictions in air transportation. … Items destined to military or PTFAS locations are excluded from using HAZMAT Service Type codes and the ‘H’ service icon on the package label. … HAZMAT mailed to, from and between APO/FPO/DPO and PTFAS locations must follow international rules for mailing.”

[^4]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=33), PDF page 33: “All hazardous materials warning labels and markings, including markings required by other federal regulatory agencies, must be displayed on the address side of the package, including the proper shipping name and UN identification numbers, unless otherwise specified. … If there is insufficient space, DOT labels or markings may be placed on an adjacent side but must never be placed on the bottom of a package or envelope. … Oriented as diamonds (diamond-shaped) and measure at least 100 mm (3.9 inches) on each side, unless otherwise specified by postal regulations. … Surface mailpieces containing hazardous materials must include one of the following endorsements:”

[^5]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=32), PDF page 32: “Mailers are required to use a unique STC within the Intelligent Mail package barcode (IMpb) and the Intelligent Mail matrix barcode (IMmb) for each domestic outbound and return package that contains hazardous materials, regardless of whether the mail is entered at origin or destination -except for packages destined for Army Post Office, Fleet Post Office, and Diplomatic Post Office (APO/FPO/DPO) locations, U.S. Possessions, Territories, and Freely Associated States (FAS), excluding Puerto Rico. … Mailers must identify whether a shipment contains hazardous materials when generating the label, including Postal Service-generated labels (e.g., from USPS Application Programming Interfaces (API), Click-N-Ship, or Merchant Returns Application). … A Service Type Code (STC) is a three-digit code that identifies the type of product or service used for a Postal Service package and designates the contents as hazardous materials. … Mailers tendering packages that contain hazardous materials to the Postal Service must use Extra Service Code (ESC) 857. … The mailer is responsible for accurately identifying the flashpoint, toxicity, corrosive, or any other hazardous properties before determining mailability. … However, combining multiple extra services (e.g., signature confirmation and insurance less than or equal to $500) is prohibited when mailing hazardous materials.”

[^6]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=98), PDF page 98: “Small consumer-type lithium-ion cells and batteries (also called secondary lithium cells or batteries), such as those used to power cell phones and laptop computers, are only mailable domestically under the following conditions. … Watt-Hour Rating per Battery: Batteries must not exceed a 100 Wh rating. … Each mailpiece must contain no more than eight cells or two batteries. … Watt-Hour Rating per Cell: Cells must not exceed a 20 Wh rating. … Weight Limit: The mailpiece must not exceed 5 pounds. … ≤ 2.7 Wh: For lithium-ion cells and batteries with a watt-hour rating up to 2.7 Wh, no mailpiece may exceed 2.5 kilograms (5.5 pounds). … The text "Surface Mail Only, Primary Lithium Batteries Forbidden for Transportation Aboard Passenger Aircraft" or "Surface Mail Only, Lithium Metal Batteries - Forbidden for Transportation Aboard Passenger Aircraft."”

[^7]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=402), PDF page 402: “Lithium metal (nonrechargeable) cells and batteries and lithium-ion (rechargeable) cells and batteries are mailable domestically via air or surface transportation when they are installed in or packed with the equipment they are intended to operate if all the requirements in 349 and this packaging instruction are met. … Lithium metal and lithium-ion batteries installed in or packed with used, damaged, or defective electronic devices (excluding devices that are new in original packaging, and manufacturer-certified new or refurbished devices) meeting all mailability requirements in 349 are mailable via surface transportation only. … Unless otherwise excepted, lithium metal and lithium-ion batteries (without equipment) are mailable domestically via surface transportation only. … Lithium-ion Battery, UN3480.”

[^8]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=96), PDF page 96: “Marking for Used Devices: Used, damaged, or defective electronic devices (refer to 349.21(e)), must be marked with "Restricted Electronic Device" and "Surface Transportation Only" on the address side of the mailpiece. … Battery Testing Standards: Each cell or battery must meet UN Manual of Tests and Criteria, Part III, 38.3, as referenced in DOT's hazardous materials regulation (49 CFR § 171.7). … Outer Packaging: Mailpieces containing lithium batteries must be packaged in rigid outer packaging unless excepted under 339.4. … Marking Requirements: DOT-approved lithium battery marks, as specified in Exhibit 325.4(a), must be applied flat (i.e., without the mark being folded) on the address side of the mailpiece and in such a manner that parts of the mark do not appear on different sides of the mailpiece. … Note: Mailpieces containing button-cell batteries installed in equipment (including circuit boards) or no more than four lithium cells or two lithium batteries installed in the equipment they operate are excepted.”

[^9]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=146), PDF page 146: “Certain animals are mailable under specified conditions. … Live Bees: 526.2 and Exhibit 526.21. … Live, Day-Old Poultry: 526.3 and Exhibit 526.33. … Warm-blooded animals, except for adult birds and specified day-old birds under the specific conditions in this section, are not mailable. … Cats or kittens. … Dogs or puppies. … Live Adult Birds: 526.4. … All snakes, turtles, and poisonous reptiles are nonmailable. … All poisonous insects and all spiders are nonmailable, except for scorpions under limited circumstances (refer to 526.5).”

[^10]: [PostalPro: USPS® Container Requirements for Adult Birds](https://postalpro.usps.com/operations/adult-bird-containers): “Shipment of adult birds must use Priority Mail Express service.”

[^11]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=29), PDF page 29: “Retail personnel must ask, "Do any of your articles contain anything liquid, fragile, perishable, or potentially hazardous, such as lithium batteries, perfume, mercury or aerosols?" … Identify Requirements: Determine applicable quantity limits, labeling, and packaging requirements for mailable contents.”

[^12]: [PRC: Mail Classification Schedule through July 12, 2026 (docx, converted to HTML with mammoth)](https://www.prc.gov/sites/default/files/mcs/MCS%20Through%2007122026.docx): “Revisions Through July 12, 2026 … HazMat Handling Fee Add $7.50 for retail or commercial parcels that contain Hazardous Materials. … HazMat Handling Fee Add $0.00 for retail or commercial parcels that contain Hazardous Materials. … HazMat Handling Fee Add $0.00 for parcels that contain Hazardous Materials. … Add $50.00 for commercial parcels if Hazardous Materials are detected, but the customer did not appropriately declare and/or label them.”

[^13]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=94), PDF page 94: “Examples (not all of which are mailable) include lithium batteries, dry ice, magnetized materials, life-saving appliances (e.g., automobile air-bags, self-inflating life vests), and asbestos. … Note: Only lithium batteries, dry ice, magnetized materials and items that can qualify as consumer commodity materials when prepared according to the standards within this section are mailable. … These batteries are also referred to as secondary or rechargeable lithium cells or batteries which are typically used in cell phones and laptop computers. … Lithium-Ion Cell or Battery: A rechargeable electrochemical cell or battery in which the positive and negative electrodes are both lithium compounds constructed with no metallic lithium in either electrode. … Lithium Metal Cell or Battery: A non-rechargeable electrochemical cell or battery utilizing lithium metal or lithium alloys as the anode.”

[^14]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=118), PDF page 118: “Service Required: Cremated remains may only be mailed domestically when sent via Priority Mail Express service, utilizing USPS-produced cremated remains packaging (BOX-CRE). … Extra Services: Additional insurance and Return Receipt are the only extra services permitted for cremated remains. … Service and Destination Verification: Cremated remains (human or animal) may be sent internationally only through Priority Mail Express International service in USPS-produced cremated remains packaging (BOX-CRE) and when the destination country permits.”

[^15]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=414), PDF page 414: “Domestic: The primary receptacle must be strong and durable and be constructed in such a manner as to protect and securely contain the contents inside and it must be properly sealed so that it is sift-proof. … All cremated remains mailings must utilize the USPS-produced Cremated Remains (BOX-CRE) outer packaging, found on usps.com. … International: A funeral urn is required as the primary receptacle. It must be sealed and sift-proof. … Insert the primary receptacle into a sealed plastic bag, then place in the shipping box and add padding to the bottom, sides, and top to ensure there is no movement of contents during transit. … It is recommended that you attach a slip of paper to the sealed plastic bag with the complete return and delivery addresses and the words “Cremated Remains” in the event the mailing label becomes”

[^16]: [DMM 113: Retail Priority Mail Express, Prices and Eligibility](https://pe.usps.com/text/dmm300/113.htm): “Items mailed containing cremated remains in their original form (ashes) and any other form (e.g., keepsakes and jewelry) must be sent via Priority Mail Express. … Priority Mail Express postage is charged for each addressed piece according to its weight and zone.”

[^17]: [Notice 123: Price List (effective October 4, 2026)](https://pe.usps.com/text/dmm300/Notice123.htm): “Notice 123 • Effective October 04, 2026 … Retail—Letters, Large Envelopes & Parcels … | 0.5 | $37.05 |”

[^18]: [DMM 503: Extra Services](https://pe.usps.com/text/dmm300/503.htm): “Extra Service fees are charged per piece in addition to correct postage.”

[^19]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=31), PDF page 31: “Hazardous materials are articles or substances designated by the United States (U.S.) Department of Transportation (DOT) as being capable of posing unreasonable risks to health, safety, or property during transportation. … Hazardous material is a designation of items that fall within one of three categories: mailable, mailable with restrictions, or prohibited. … DOT regulates the carriage of hazardous materials within the U.S. under the Code of Federal Regulations Title 49 (49 CFR). … Postal Service mailing standards for hazardous materials generally adhere to 49 CFR, but also include many additional limitations and prohibitions.”

[^20]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=40), PDF page 40: “Every hazardous material is assigned to one of nine hazard classes in 49 CFR § 172.101 as defined in 49 CFR § 173. … Class 1: Explosives. … Class 2: Gases. … Class 3: Flammable and Combustible Liquids. … Class 4: Flammable Solids. … Class 5: Oxidizing Substances, Organic Peroxides. … Class 6: Toxic Substances and Infectious Substances. … Class 7: Radioactive Materials. … Class 8: Corrosives. … Class 9: Miscellaneous Hazardous Materials. … Appendix A lists the hazardous materials from 49 CFR and identifies eligibility for mailing in the domestic mail via air and surface transportation. … This table can be used to determine the mailability of a hazardous material if the proper shipping name of the material is known. … Where mailpieces are tendered in containers, pallets, or other mail transport equipment (refer to Handbook PO-502, Mail Transport Equipment), hazardous-materials mailpieces must be presented in a separate receptacle from non-hazardous-materials mailpieces.. … Clearly mark an exterior side of all containers with hazardous- materials mailpieces as "HAZMAT."”

[^21]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=165), PDF page 165: “Battery: Batteries must be installed in the equipment being shipped. … Quantity Limits: Each shipment may contain a maximum of four lithium cells or two lithium batteries. … Marking or Labeling: Mailpieces must not display markings or labels identifying the contents as lithium batteries. … Used, damaged, defective, or recalled lithium batteries and used, damaged, or defective electronic devices (excluding devices that are new in original packaging, and manufacturer-certified new or refurbished devices) containing or packaged with lithium batteries are prohibited and may not be mailed internationally or to, from, or between APO, FPO, or DPO locations under any circumstances.”

[^22]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=101), PDF page 101: “Domestic Mail via Air Transportation: Dry ice is permitted in quantities of up to 5 pounds per mailpiece. … Domestic Mail via Surface Transportation: Dry ice is permitted and must comply with Packaging Instruction 9A in Appendix C. … International Mail: Dry ice is prohibited.”

[^23]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=399), PDF page 399: “For surface transportation, a mailpiece may contain more than 5 pounds of dry ice. … Each mailpiece must be clearly marked on the address side with the name of the contents being cooled (such as frozen medical specimens, steaks) and the net weight of the dry ice. … For air transportation, each mailpiece must bear a Class 9 DOT miscellaneous hazardous material warning label and must be clearly marked “Carbon Dioxide Solid, UN1845” Or “Dry Ice, UN1845.” … For surface transportation, each mailpiece must be clearly marked “Surface Only” or “Surface Mail Only” and “Carbon Dioxide Solid, UN1845” or “Dry Ice, UN1845.””

[^24]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=100), PDF page 100: “Packages containing dry ice must be vented to allow the release of carbon dioxide gas and to comply with 49 CFR § 173.217 and 175.10(a)(10). … Prohibited, unless approved by the director, Product Classification. … Dry ice (carbon dioxide solid) is produced by expanding liquid carbon dioxide to vapor and compacting the material into blocks. … Dry ice is primarily used to keep other items cool, including both mailable hazardous materials or nonhazardous items, such as medical specimens or foods. … This resulting gas is denser than air and may displace oxygen in confined spaces, creating a risk of suffocation. … When dry ice is enclosed in a thick metal or other restrictive type of container, internal pressure builds up and could cause the container to rupture or explode.”

[^25]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=108), PDF page 108: “Intoxicating liquors are beverages with an alcohol content of 0.5 percent or more by weight and are taxable per Chapter 51 of the United States (U.S.) Internal Revenue Service (IRS) Code. … A product containing intoxicating liquor is determined to be mailable if it: … Complies with applicable IRS and U.S. Food and Drug Administration (FDA), regulations. … Is not classified as a taxable alcoholic beverage. … Is not poisonous. … Is not flammable. … Examples of these mailable products include cold remedies, cooking wine, and mouthwash. … Intoxicating liquor is exempt from the prohibition and may be mailed between federal or state agency employees for official use (e.g., for testing purposes).”

[^26]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=109), PDF page 109: “Intoxicating liquors and taxable liquors, including those obtained under a prescription or as a collector's item, are nonmailable. … Firearm: Any device, including a starter gun, which will, or is designed to, or may readily be converted to, expel a projectile by the action of an explosive; the frame or receiver of any such weapon; any firearm muffler or firearm silencer; or any destructive device; but the term shall not include antique firearms (except antique firearms meeting the description of a handgun or of a firearm capable of being concealed on a person). … Handgun (Including Pistols and Revolvers): A firearm with a short stock designed to be held and fired by the use of a single hand and subject to 431.1, or a combination of parts from which a handgun can be assembled.”

[^27]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=169), PDF page 169: “Materials that are nonmailable domestically are also prohibited in international mail. … Intoxicating liquor.”

[^28]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=21), PDF page 21: “Under 18 U.S.C. § 1716, all matter that is outwardly or of its own force dangerous or injurious to life, health, or property is nonmailable. … Postmasters may consult with the Pricing and Classification Service Center (PCSC) in making these determinations.”

[^29]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=17), PDF page 17: “The definitions of hazardous materials, restricted matter, and perishable matter are as follows: … Restricted matter includes intoxicating liquors, firearms, construction materials, certain liquids, powders, controlled substances, hemp products, sharp objects, tobacco products, and unsolicited promotional items. … Perishable Matter: Anything that can deteriorate in the mail and thereby lose value, create a health hazard, or cause an obnoxious odor, nuisance, or disturbance, under ordinary mailing conditions.”

[^30]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=107), PDF page 107: “Restricted matter is a designation of items that fall within one of three categories: mailable, mailable with restrictions, or prohibited. … Restricted matter includes items on which mailing restrictions have been imposed, generally, by federal law. … The mailer is responsible for ensuring that all Postal Service requirements, as well as any applicable federal and state laws and local ordinances applicable to the shipment of restricted matter, have been met. … Where doubt exists about mailability of any article that is considered to be restricted matter, a request for a ruling may be made to the local postmaster (refer to 215).”

[^31]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=143), PDF page 143: “Perishable matter is a designation of items that fall within one of three categories: mailable, mailable with restrictions, or prohibited. … Examples of perishable matter include mailable types of live animals, food items, and plants. … Mailable perishable matter may be sent at the mailer's own risk when it is packaged as required and when it can be delivered within appropriate and reasonable time limits to prevent deterioration. … The Live Animal and Perishable Handling Fee is a fee assessed on all live animals and perishable items (e.g., fruit, meat) entered at retail and commercial rates for Priority Mail Express, Priority Mail, and USPS Ground Advantage.”

[^32]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=185), PDF page 185: “In the domestic mail, generally only those hazardous materials meeting all of the following criteria are eligible for mailing: … Designated by DOT as being eligible to be transported under its Limited Quantity Provision, … Packaged and distributed in a quantity and form intended or suitable for retail sale, and … Designed for consumption by individuals for their personal care or household uses (i.e. consumer commodity material) are eligible for mailing and subject to postal quantity limitations.”

[^33]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=38), PDF page 38: “Postal Service hazardous materials regulations are based on the mode of transportation (air or surface); therefore, compliance with the specific mode of transportation is required. … Shipping papers are referred to as a Shipper's Declaration for Dangerous Goods when being offered for air transportation according to the Dangerous Goods Regulations of the International Air Transport Association (IATA). … Air Transportation: Most mailable hazardous materials sent by air must be accompanied by shipping documentation. … Surface Transportation: Certain hazardous materials sent by surface transportation may require shipping documentation. … Domestically, a shipping paper means a shipping order, bill of lading, waybill, or manifest, per 49 CFR § 171.8, which identifies hazardous materials being offered for surface transportation. … Completed and signed in triplicate by the mailer. … Enclosed in an envelope, or similar carrier, that can be easily opened and resealed, and securely affixed to the outside of the mailpiece to allow access to the document during inspection.”

[^34]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=39), PDF page 39: “Hazardous materials shipped via Priority Mail Express or Priority Mail must be eligible for air transportation and meet the following requirements: … All mailable hazardous materials sent as Priority Mail Express or Priority Mail must meet the requirements for air transportation, regardless of the transportation method used. … The following types of hazardous materials are always prohibited on air transportation: … Flammable materials (gases, liquids, and solids). … Radioactive materials. … UN3090 lithium metal batteries (including lithium alloy batteries) and UN3480 lithium-ion batteries (including lithium polymer batteries). … Mailpieces must be prepared according to the applicable Packaging Instructions in Appendix C.”

[^35]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=426), PDF page 426: “Surface transportation requirements apply to all mailable hazardous materials sent at the Parcel Select Lightweight or USPS Ground Advantage prices and must meet the requirements that apply to surface transportation. … Small quantity is the maximum amount of a specific hazardous material that is not subject to any requirements other than those in 49 CFR § 173.4. … UN Number The United Nations (UN) four-digit identification number assigned to a hazardous material that is recognized for use in international and domestic commerce and transportation. … The United Nations (UN) four-digit identification number assigned to a hazardous material that is recognized for use in international and domestic commerce and transportation.”

[^36]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=161), PDF page 161: “Almost all dangerous materials are prohibited in international mail. … Packages containing dangerous goods going to destinations outside the customs territory of the United States must follow international regulations for package content and are subject to the same customs clearance procedures required for international mail. … Therefore, shipments to U.S. Possessions, Territories, and Freely Associated States must follow the guidelines in 622 for mailable dangerous goods.”

[^37]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=22), PDF page 22: “If information is insufficient to determine mailability or if the item’s mailability is uncertain, mailers may submit an SDS and the following information to Product Classification (refer to 214 for contact information) or the PCSC (refer to 213 for contact information): … After the PCSC issues an initial ruling, the mailer may appeal to the director, Product Classification, USPS Headquarters, Washington, DC, who has the authority to render a decision on the appeal. … To determine mailability, mailers must provide a Safety Data Sheet (SDS), formerly known as Material Safety Data Sheet (MSDS), along with detailed information about the material to the Post Office or acceptance facility.”

[^38]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=419), PDF page 419: “Dangerous goods is the term used to describe hazardous materials shipped in international commerce.”

[^39]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=43), PDF page 43: “Consumer Commodity is a hazardous material that is packaged and distributed in a quantity and form intended or suitable for retail sale and designed for consumption by individuals for their personal care or household uses. … Certain hazardous materials in Classes 2 and 3 and Division 6.1 may qualify as consumer commodity subject to the applicable 49 CFR requirements and are reclassed as ID8000 when authorized to be carried on passenger aircraft.”

[^40]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=48), PDF page 48: “Domestic Mail via Air Transportation: All explosives are prohibited. … Domestic Mail via Surface Transportation: Generally, explosives are prohibited, with exceptions for Division 1.4S toy propellant devices and safety fuses that have been approved by the director, Product Classification before mailing (refer to 214 for contact information).”

[^41]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=44), PDF page 44: “This classification is only applicable for certain materials that pose a limited hazard during transportation due to their form, quantity, and packaging and includes materials previously classified as Other Regulated Materials for Domestic (ORM-D) (refer to Appendix D). … These materials are prohibited in Priority Mail Express and Priority Mail. … An excepted quantity refers to a defined amount of a specific hazardous material that is eligible for transport aboard passenger aircraft and is exempt from most DOT requirements (e.g., packaging, marking, labeling) under 49 CFR § 173.4a. … The excepted quantity provision can be used in domestic air or surface transportation (highway, rail, or vessel). … Placing surface transportation labels or associated text markings on Priority Mail Express or Priority Mail to circumvent air transportation is prohibited.”

[^42]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=45), PDF page 45: “30 g (1 ounce) for solids. … 30 ml (1 ounce) for liquids. … This provision applies only to domestic highway and rail transportation mail and its use is prohibited to international or APO/FPO/DPO destinations.”

[^43]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=418), PDF page 418: “Aerosol means any nonrefillable metal receptacle containing a gas that is compressed, liquified, or dissolved under pressure, the sole purpose of which is to expel a nonpoisonous (other than a Division 6.1 Packing Group III material) liquid, paste, or powder and fitted with a self-closing release device allowing the contents to be ejected by the gas.”

[^44]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=188), PDF page 188: “Aerosols, flammable (each not exceeding 1 L capacity) 2.1 UN1950 n/a Prohibited 2A … Aerosols, nonflammable (each not exceeding 1 L capacity) 2.2 UN1950 n/a 2B 2B”

[^45]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=51), PDF page 51: “Division 2.1 (flammable gases) and Division 2.3 (toxic gases) are prohibited. … Division 2.2 (nonflammable gases) are generally permitted if the material can qualify as an ID8000 material (refer to 335) and meet quantity limits and packaging requirements (refer to 342.3 and 342.4). … Division 2.1 (flammable gases) and Division 2.2 (nonflammable gases) are generally permitted if the material can qualify as a Limited Quantity surface material and meet the quantity limits and packaging requirements (refer to 342.3 and 342.4). … International Mail: All gases are prohibited.”

[^46]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=52), PDF page 52: “Aerosol Paint Products: Aerosol paint products that are defined as flammable compressed gases are acceptable in the domestic mail via surface transportation only if they can qualify as a Limited Quantity ground material and meet the quantity limitations and applicable packaging requirements in 342.3 and 342.4.”

[^47]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=134), page 135: “Hazardous Materials Class 3 - Package (Hand sanitizer, rubbing alcohol, ethanol base products, flammable liquids etc.)”

[^48]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=55), PDF page 55: “Domestic Mail via Air Transportation: Flammable liquids are prohibited. … Domestic Mail via Surface Transportation: Flammable liquids with a flashpoint at or below 20° F (-7° C) are prohibited. … Other flammable liquids may be mailed if they qualify as a Limited Quantity surface material and meet the criteria in Exhibit 343.21.”

[^49]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=421), PDF page 421: “Flashpoint means the minimum temperature at which a liquid gives off vapor within a test vessel in sufficient concentration to form an ignitable mixture with air near the surface of the liquid. … Hazard class means the category to which a hazardous material is assigned under the definitions set by DOT in 49 CFR.”

[^50]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=58), PDF page 58: “An approval letter must be obtained from the PCSC director prior to mailing. … Flammable liquids or solids containing ethanol (ethyl alcohol) are mailable by domestic air only with prior written authorization.”

[^51]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=73), PDF page 73: “Vendors providing complete medical waste or sharps waste mailing container systems (including all component parts required to safely mail such waste to a storage or disposal facility) must obtain authorization from the Postal Service prior to mailing.”

[^52]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=70), PDF page 70: “Domestic Mail: Infectious substances are mailable only when intended for medical or veterinary use, research, or laboratory certification related to public health, and must be properly prepared to withstand shocks, pressure changes, and other conditions incident to ordinary handling in transit. … International Mail: Category A infectious substances are nonmailable. Category B infectious substances (as defined in 346.12(a)2) are permitted when they are intended for medical or veterinary use, research, or laboratory certification related to public health, and are properly prepared for mailing. The mailer must receive written approval from the director, Product Classification.”

[^53]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=71), PDF page 71: “Category B infectious substances that meet the definition in 346.12(a)2 require triple packaging, must adhere to the packaging requirements in 49 CFR § 173.199, and be shipped via Priority Mail or Priority Mail Express.”

[^54]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=422), PDF page 422: “Limited Quantity is the maximum amount of a specific hazardous material that is exempted from the labeling or packaging requirements in 49 CFR.”

[^55]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=51), page 47: “A hazardous material that is packaged and distributed in a quantity and form intended or suitable for retail sale and designed for consumption by individuals for their personal care or household use purposes. This term can include certain drugs or medicines. Not all hazardous material permitted to be mailed as a limited quantity can qualify as a consumer commodity.”

[^56]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=425), PDF page 425: “Safety Data Sheet (SDS) is a document that details the physical characteristics and health hazards of a chemical or hazardous product.”

[^57]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=101), page 97: “Any article or substance designated by the U.S. Department of Transportation (DOT) as being capable of posing an unreasonable risk to health, safety, and property during transportation. Not all hazardous materials are mailable, and those that are mailable must be prepared, documented, and marked according to specific requirements.”

[^58]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=95), PDF page 95: “These batteries are also referred to as primary or nonrechargeable lithium cells or batteries, and are often used in consumer products such as cameras and flashlights. … Lithium battery: A unit composed of one or more lithium cells which are electrically connected together by a permanent means, including case, terminals, and markings.”

[^59]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=99), PDF page 99: “Original Packaging: Lithium-ion cells and batteries must be in their sealed packaging. … Weight Limit: The mailpiece must not exceed 5 pounds. … The text "Surface Mail Only, Secondary Lithium Batteries Forbidden for Transportation Aboard Passenger Aircraft" or "Surface Mail Only, Lithium-ion Batteries - Forbidden for Transportation Aboard Passenger Aircraft."”

[^60]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=97), PDF page 97: “Lithium Content per Cell: Each cell must not exceed more than 1.0 gram of lithium. … Lithium Content per Battery: Each battery must not exceed more than 2.0 grams of lithium content. … Original Packaging: Lithium metal cells and batteries must be mailed in the sealed packaging. … Weight Limits (≤ 0.3 g): For cells and batteries containing up to 0.3 grams of lithium, no mailpiece may exceed 2.5 kilograms (5.5 pounds). … There is no maximum number of cells or batteries per mailpiece.”

[^61]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=403), PDF page 403: “Lithium-ion Battery contained in equipment, UN3481. … Lithium-ion Battery packed with equipment, UN3481. … Lithium Metal Battery, UN3090. … Lithium Metal Battery contained in equipment, UN3091. … Lithium Metal Battery packed with equipment, UN3091.”

[^62]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=400), PDF page 400: “For air transportation, a properly completed Shipper's Declaration for Dangerous Goods must be prepared in triplicate and affixed to the outside of the mailpiece. … Note: A shipper’s declaration and a Class 9 DOT warning label are not required for dry ice sent via domestic surface mail.”

[^63]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=36), PDF page 36: “Packages containing hazardous materials must display the appropriate DOT hazardous materials warning label(s) and marking(s) as outlined in 49 CFR § 172.407 through 172.446. … Only the following hazardous materials warning labels in Exhibit 325.4a, Exhibit 325.4b, and Exhibit 325.5 are permitted in Postal Service networks. … Note: The sizes and colors of the labels shown in exhibits are for reference only and do not meet DOT size and color standards unless explicitly noted.”

[^64]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=37), PDF page 37: “The diamond-shaped marking must have black top and bottom portions with a white or contrasting center background. … For transportation by aircraft, the air Limited Quantity mark must include a black ''Y'' in the center of the diamond-shaped mark and be clearly visible. Mailpieces intended for air transport must also display the proper shipping name, identification number, and appropriate DOT-associated marking when required for the hazard class shipped in accordance with this publication. … For surface transportation, a Limited Quantity ground mark (diamondshaped) is not required to include the proper shipping name and identification number.”

[^65]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=129), page 130: “An extra service code representing general HAZMAT shipment is required. It is strongly recommended that an additional extra service that identifies the specific category of HAZMAT is also used.”

[^66]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=126), page 127: “The Postal Service requires the use of a service icon of 'H' in the upper left corner when the package being shipped domestically contains an item that is hazardous material to further improve visual identification.”

[^67]: [Updated List: Service Type Codes for Intelligent Mail® Package Barcode (IMpb)](https://postalpro.usps.com/mnt/glusterfs/2026-06/Service_Type_Codes_Appendix_I_06242026.xlsx), Effective June 24, 2026, code 116: Code: 116; Description: Priority Mail USPS Tracking Hazardous Materials; Mail class: PM; Banner text: USPS TRACKING # HAZMAT; Extra service codes: 920, 857

[^68]: [Ancillary Services for Parcel Select and Parcel Select Lightweight FAQs](https://postalpro.usps.com/mnt/glusterfs/2022-07/Ancillary%20Services%20Parcel%20Select%20and%20Parcel%20Select%20Lightweight%20FAQs%20(002).pdf#page=2), PDF page 2: “Parcel Select Lightweight pieces containing hazardous materials must bear the endorsement “Address Service Requested,” “Forwarding Service Requested,” or “Return Service Requested.””

[^69]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=34), PDF page 34: “The endorsement "Change Service Requested" is not permitted for mailpieces containing hazardous materials.”

[^70]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=424), PDF page 424: “Proper shipping name is the name of a hazardous material that must be used to identify a substance or article in the shipping documents and on the packaging, as required.”

[^71]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=475), page 476: “Service Type Codes are designators used to represent USPS classes of mail in conjunction with the type of Extra Service(s) being requested.”

[^72]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=111), PDF page 111: “Handguns, and other firearms capable of being concealed on the person, are nonmailable unless mailed between the parties listed in 432, after the filing of an affidavit or statement described in 432.22 or 432.24, and are subject to the following: … All regulated firearms must be mailed using a USPS product or Extra Service that provides tracking and signature capture at delivery, unless shipped between licensed dealers, manufacturers, or importers. … The Postal Service may require the mailer to open packages containing firearms or air guns or give written certification that the weapon is unloaded and not concealable. … No markings of any kind that indicate the nature of the contents may be placed on the outside wrapper or container of any mailpiece containing mailable firearms.”

[^73]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=113), PDF page 113: “Handguns may be mailed between licensed firearm manufacturers, dealers, and importers in customary trade shipments, or for repairing or replacing parts. … Federal firearms licensee manufacturers, dealers, or importers are exempt from the affidavit requirement under 432.22 but must file a statement with the postmaster on PS Form 1508, Statement by Shipper of Firearms, signed by the mailer to confirm that:”

[^74]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=112), PDF page 112: “Subject to 432.22, handguns may be mailed by licensed firearm manufacturers, dealers, importers, or authorized agents of federal, state, territory, or district governments, only upon filing the required affidavit or certificate and when addressed to a person in one of the following categories for use in the person's official duties:”

[^75]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=114), PDF page 114: “Except under 431.2, unloaded rifles and shotguns are mailable. … Mailers must comply with the rules and regulations per 27 CFR, Part 478, as well as state and local laws.”

[^76]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=116), PDF page 116: “A switchblade knife, as defined in 441.2, is mailable only to the following categories of addressees: … Government Supply or Procurement Officials: Designated officers or employees ordering, procuring, or purchasing switchblade knives in connection with the activities of their respective governments or organizations, such as: … Manufacturers or Dealers: Authorized manufacturers or bona fide dealers may mail switchblade knives to addresses within one of the categories listed above in connection with official procurement or resale. … Sharp instruments include all sharp-pointed or sharp-edged implements, such as knives, tools, ice picks, razor blades, stilettos, or similar devices. … A switchblade knife features a blade that opens automatically by hand pressure applied to a button or other device on the handle, or through inertia, gravity, or both.”

[^77]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=117), PDF page 117: “All sharp-pointed or sharp-edged instruments (e.g., knives, tools, ice picks, razor blades) that are otherwise mailable must be securely packaged in a strong container. … Sufficient cushioning material must be used to protect the sharp points and edges from cutting through the outer packaging during normal Postal Service handling. … Liquids that are nonhazardous (i.e., not regulated as hazardous materials) are mailable provided they are properly packaged as specified in 451.3. … Powders must be packed in sift-proof containers or other containers that are sealed in durable sift-proof outer containers. … Any matter that is a source of an obnoxious odor is nonmailable.”

[^78]: [PostalPro: Cigarettes, Smokeless Tobacco, and Electronic Nicotine Delivery Systems (ENDS)](https://postalpro.usps.com/product-classification/tobacco): “Cigarettes, Smokeless Tobacco, and Electronic Nicotine Delivery Systems (ENDS) are generally non-mailable, unless authorized by an exception, if all PACT ACT related conditions of mailability are met.”

[^79]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=115), PDF page 115: “Postmasters are not authorized to give opinions on the legality of any shipment of firearms. … Mailers requesting additional information should be referred to the ATF.”

[^80]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=50), PDF page 50: “Ammunition that is regulated as a Class 1 explosive and designed to be fired from a pistol, revolver, rifle, or shotgun, as well as associated primers and blank cartridges (including those designed for tools) and propellant powder for use in any firearm, is prohibited from mailing.”

[^81]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=415), PDF page 415: “detached from the outer packaging after acceptance.”

[^82]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=133), PDF page 133: “Mailings under this exception are permitted only for business purposes between eligible businesses or for regulatory purposes between such businesses and eligible government agencies.”

[^83]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=124), PDF page 124: “Authorized DEA registrants who wish to receive lawfully obtained unused or unwanted pharmaceuticals from ultimate users for the purpose of disposal must obtain Postal Service authorization.”

[^84]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=15), PDF page 15: “Regulations for nonmailable matter in written, printed, or graphic form are found in the Domestic Mail Manual (DMM) 601.8.0, 508.9.0, and 508.10.0.”

[^85]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=151), page 147: “Matter that would be otherwise mailable that includes certain solicitations, lottery and certain advertising matter, and matter using any fictitious name, title, or address in conducting any scheme or device in violation of law. … Matter that would be otherwise mailable that includes certain solicitations, lottery and certain advertising matter, and matter using any fictitious name, title, or address in conducting any scheme or device in violation of law. The solicitations may be either in guise of bills, invoices, or statements of account, or they may deceptively imply federal connection, approval, or endorsement.”

[^86]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=188), PDF page 188: “A USPS order requested by the addressee of a pandering advertisement that directs the sender to make no further mailing to that addressee.”

[^87]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=183), page 179: “The PCSC processes customer applications to mail at Nonprofit Standard Mail prices, handles Sexually Oriented Advertising and Pandering Prohibitory Orders, manages the Centralized Postage Payment system, and issues final agency decisions.”

[^88]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=195), page 191: “Any item on which certain mailing restrictions have been imposed for legal reasons other than risk of harm to persons or property involved in moving the mail and that require specific endorsements and markings. Examples include intoxicating liquors, abortive or contraceptive devices, odd-shaped items in envelopes, motor vehicle master keys, locksmithing devices as well as odor-producing materials, certain liquids and powders, battery-powered devices, and certain tobacco products.”

[^89]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=147), PDF page 147: “Honeybees: Acceptable to mail only via surface transportation (except for queen honeybees; refer to b.). … Queen Honeybees: May be shipped via air or surface transportation.”

[^90]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=149), PDF page 149: “Age: Poultry must be no more than 24 hours old. … Container Requirements: Poultry must be presented for mailing in the original, unopened hatchery box from the hatchery of origin.”

[^91]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=152), PDF page 152: “Mailers must use containers that have been pre-approved by the director, Product Classification.”

[^92]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=153), PDF page 153: “Under this limitation, scorpions are mailable only when sent for the purposes of medical research or the manufacturing of antivenin. … Small, harmless, cold-blooded animals, except for snakes, turtles, and turtle eggs, are mailable only when they meet requirements specified in Exhibit 526.6.”

[^93]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=144), PDF page 144: “Shipping containers for mailable live animals must, at a minimum, be made of 275-pound test, double-wall, corrugated, weather-resistant fiberboard (W5c) or equivalent. … USPS-produced packaging, including Flat Rate containers, is not eligible for use.”

[^94]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=145), PDF page 145: “Each mailpiece must display a complete return address and be marked on the address side with a description of the contents (e.g., "Live Animals," "Live Honeybees"). … Mailpieces marked with "If Undeliverable, Abandon" are not eligible for mailing. … Any mailpiece containing live animals that cannot be delivered to the addressee or returned to the sender within 72 hours (for live, day-old poultry) or within the delivery period marked on the package (for other mailable animals) must be disposed of immediately.”

[^95]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=156), PDF page 156: “Fresh fruits and vegetables are nonmailable unless presented in a dry (not dried) condition. … Other perishable foods that decompose easily or cannot reach their destination without spoiling are nonmailable.”

[^96]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=157), PDF page 157: “Meats and meat products are mailable in domestic mail only when compliant with U.S. Department of Agriculture (USDA) regulations. … Eggs are mailable in domestic mail when the following conditions are met: … Cushioning: Each egg is individually cushioned. … If dry ice is used to maintain temperature during transport, its use must adhere to mailing conditions specified in 349.3. … Plants and plant products are mailable within the United States, its territories, and possessions, but are subject to certain prohibitions and restrictions imposed by federal agricultural and conservation statutes. … Under 39 U.S.C. § 3014(b), any plant, plant product, or other article capable of carrying a dangerous plant disease or insect infestation is nonmailable from a quarantined area, if shipping such an item is prohibited by the U.S. Department of Agriculture (USDA) Plant Protection Act issued under 7 U.S.C. § 7701.”

[^97]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=163), PDF page 163: “Under specific circumstances, only biological substances, limited amounts of radioactive materials, certain magnetized materials, and lithium batteries installed in the equipment they intend to operate are eligible to be sent in international mail. … Mailers shipping dangerous goods internationally, including to APO/FPO/ DPO and U.S. Possessions, Territories, and Freely Associated States destinations utilizing PC Postage or USPS Ship platforms, must include Extra Service Code (ESC) 857 and incorporate the applicable content- specific ESC listed in Appendix G and Publication 199.”

[^98]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=162), PDF page 162: “Because individual countries have unique prohibitions and restrictions, it is always necessary to consult the ICL in the IMM to be certain that an otherwise mailable dangerous material is acceptable for shipment to a specific country.”

[^99]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=167), PDF page 167: “The requirements and prohibitions that apply to the mailing of firearms in domestic mail, as stated in Chapter 4, also apply to international mail subject to any restrictions in the ICL in the IMM.”

[^100]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=170), PDF page 170: “Most live or dead animals are nonmailable in international mail.”

[^101]: [Publication 52: Hazardous, Restricted, and Perishable Mail](https://pe.usps.com/cpim/ftp/pubs/Pub52/pub52.pdf#page=25), PDF page 25: “If they remain legible, the packaging may be considered nonmailable and will be treated as containing the indicated materials. … Common examples of reused packaging include boxes for cleaning supplies or alcoholic beverages. … Postal Service employees are not permitted to alter or remove labels or markings, even if requested to do so by the mailer.”

[^102]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=19), page 20: “There are no thresholds for Hazmat Quality, all packages must follow proper Hazmat packaging rules or be subject to noncompliance fees.”

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