**Item category:** Glues

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic

**Conditions:** Some glues may only be sent by ground transportation.

> Some glues may only be sent by ground transportation.

Source: <https://www.usps.com/ship/shipping-restrictions.htm>

Glues — Postal shipping restrictions by item category


**Item category:** Glycerol-1,3-dinitrate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Glycerol-1,3-dinitrate Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Glycerol-1,3-dinitrate — Postal shipping restrictions by item category


**Item category:** Glycerol alpha-monochlorohydrin

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2689, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Glycerol alpha-monochlorohydrin 6.1 UN2689 III 6A 6A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Glycerol alpha-monochlorohydrin — Postal shipping restrictions by item category


**Item category:** Glycerol gluconate trinitrate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Glycerol gluconate trinitrate Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Glycerol gluconate trinitrate — Postal shipping restrictions by item category


**Item category:** Glycerol lactate trinitrate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Glycerol lactate trinitrate Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Glycerol lactate trinitrate — Postal shipping restrictions by item category


**Item category:** Grenades, hand or rifle, with bursting charge

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 1.1D, UN0284, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Grenades, hand or rifle, with bursting charge 1.1D UN0284 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Grenades, hand or rifle, with bursting charge — Postal shipping restrictions by item category


**Item category:** Grenades, practice, hand or rifle

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 1.3G, UN0318, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Grenades, practice, hand or rifle 1.3G UN0318 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Grenades, practice, hand or rifle — Postal shipping restrictions by item category


**Item category:** Guanyl nitrosaminoguanylidene hydrazine (dry)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Guanyl nitrosaminoguanylidene hydrazine (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Guanyl nitrosaminoguanylidene hydrazine (dry) — Postal shipping restrictions by item category


**Item category:** Guanyl nitrosaminoguanylidene hydrazine, wetted with not less than 30 percent water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 1.1A, UN0113, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Guanyl nitrosaminoguanylidene hydrazine, wetted with not less than 30 percent water, by mass 1.1A UN0113 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Guanyl nitrosaminoguanylidene hydrazine, wetted with not less than 30 percent water, by mass — Postal shipping restrictions by item category


**Item category:** Guanyl nitrosaminoguanyltetrazene (dry)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Guanyl nitrosaminoguanyltetrazene (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Guanyl nitrosaminoguanyltetrazene (dry) — Postal shipping restrictions by item category


**Item category:** Guanyl nitrosaminoguanyltetrazene, wetted or Tetrazene, wetted with not less than 30 percent water or mixture of alcohol and water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 1.1A, UN0114, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Guanyl nitrosaminoguanyltetrazene, wetted or Tetrazene, wetted with not less than 30 percent water or mixture of alcohol and water, by mass 1.1A UN0114 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Guanyl nitrosaminoguanyltetrazene, wetted or Tetrazene, wetted with not less than 30 percent water or mixture of alcohol and water, by mass — Postal shipping restrictions by item category


**Item category:** Hafnium powder, dry

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 4.2, UN2545, packing group I, II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hafnium powder, dry 4.2 UN2545 I, II, III Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hafnium powder, dry — Postal shipping restrictions by item category


**Item category:** Hafnium powder, wetted with not less than 25 percent water (a visible excess of water must be present) (a) mechanically produced, particle size less than 53 microns; (b) chemically produced, particle size less than 840 microns

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 4.1, UN1326, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hafnium powder, wetted with not less than 25 percent water (a visible excess of water must be present) (a) mechanically produced, particle size less than 53 microns; (b) chemically produced, particle size less than 840 microns 4.1 UN1326 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hafnium powder, wetted with not less than 25 percent water (a visible excess of water must be present) (a) mechanically produced, particle size less than 53 microns; (b) chemically produced, particle size less than 840 microns — Postal shipping restrictions by item category


**Item category:** Hairspray (aerosol)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic US

**Conditions:** Classified as flammable aerosol. Requires hazmat declaration and rigid outer packaging. Cannot be shipped in poly mailers or padded envelopes. $50 noncompliance fee if undeclared, effective July 12, 2026.

> Hairspray | Flammable aerosol | UN1950

Source: <https://selleressentials.com/usps-hazmat-noncompliance-fee-2026/>

Hairspray (aerosol) — Postal shipping restrictions by item category

carrier, conditions, item_category, scope


**Item category:** Hairspray

**Carrier:** USPS

**Restriction type:** hazmat declaration required

**Scope:** commercial package shipments

**Conditions:** Listed by the Department of Transportation as posing a significant safety risk while being transported; $7.50 hazmat handling fee for Priority Mail; $50 noncompliance fee for packages not properly declared and labeled across all commercial packages including Ground Advantage (effective July 12 2026)

> Essential oils, nail polish (and nail polish remover), perfumes and colognes, hand sanitizer, inks, stains and varnishes, hairspray, and electronics with a lithium battery are among the products listed by the Department of Transportation as posing a significant safety risk while being transported.

Source: <https://www.ecommercebytes.com/2026/07/05/new-usps-noncompliance-fee-could-take-sellers-by-surprise/>

Hairspray — Postal shipping restrictions by item category


**Item category:** Hand sanitizer

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic US

**Conditions:** Classified as flammable liquid (alcohols). Requires hazmat declaration and compliant packaging. $50 noncompliance fee if undeclared, effective July 12, 2026.

> Hand sanitizer | Flammable liquid (alcohols) | UN1987

Source: <https://selleressentials.com/usps-hazmat-noncompliance-fee-2026/>

Hand sanitizer — Postal shipping restrictions by item category


**Item category:** Hand sanitizer

**Carrier:** USPS

**Restriction type:** hazmat declaration required

**Scope:** commercial package shipments

**Conditions:** Listed by the Department of Transportation as posing a significant safety risk while being transported; $7.50 hazmat handling fee for Priority Mail; $50 noncompliance fee for packages not properly declared and labeled across all commercial packages including Ground Advantage (effective July 12 2026)

> Essential oils, nail polish (and nail polish remover), perfumes and colognes, hand sanitizer, inks, stains and varnishes, hairspray, and electronics with a lithium battery are among the products listed by the Department of Transportation as posing a significant safety risk while being transported.

Source: <https://www.ecommercebytes.com/2026/07/05/new-usps-noncompliance-fee-could-take-sellers-by-surprise/>


**Item category:** Hand Sanitizer

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic

**Conditions:** It is prohibited to send these materials by International Mail including APO/FPO/DPO (military) destinations.

> It is prohibited to send these materials by International Mail including APO/FPO/DPO (military) destinations.

Source: <https://www.usps.com/ship/shipping-restrictions.htm>

Hand Sanitizer — Postal shipping restrictions by item category


**Item category:** handguns - authorized military and law enforcement

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** domestic mail - to authorized military and law enforcement persons

**Conditions:** May be mailed by licensed firearm manufacturers, dealers, importers, or authorized government agents only upon filing required affidavit or certificate, addressed to military officers, national guard officers, law enforcement officers, authorized Postal Service employees, or federal enforcement officers for official duties

> 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

Source: <https://pe.usps.com/text/pub52/pub52c4_010.htm>

handguns - authorized military and law enforcement — Postal shipping restrictions by item category


**Item category:** handguns - between licensed FFL dealers

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** domestic mail - between licensed firearm manufacturers, dealers, and importers

**Conditions:** Handguns may be mailed between licensed firearm manufacturers, dealers, and importers in customary trade shipments or for repairing or replacing parts

> Handguns may be mailed between licensed firearm manufacturers, dealers, and importers in customary trade shipments, or for repairing or replacing parts.

Source: <https://pe.usps.com/text/pub52/pub52c4_010.htm>

handguns - between licensed FFL dealers — Postal shipping restrictions by item category


**Item category:** handguns - general prohibition

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail - general public

**Conditions:** Handguns and other firearms capable of being concealed on the person are nonmailable unless mailed between authorized parties with required affidavit or statement

> Handguns, and other firearms capable of being concealed on the person, are nonmailable unless mailed between the parties listed in 432

Source: <https://pe.usps.com/text/pub52/pub52c4_010.htm>

handguns - general prohibition — Postal shipping restrictions by item category

carrier, conditions, item_category, restriction_type


**Item category:** Hazardous Materials (HAZMAT)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic

**Conditions:** Some HAZMAT can only be sent by ground transportation—it can’t go on airplanes.

> Some HAZMAT can only be sent by ground transportation—it can’t go on airplanes.

Source: <https://www.usps.com/ship/shipping-restrictions.htm>

Hazardous Materials (HAZMAT) — Postal shipping restrictions by item category


**Item category:** Hazardous materials shipped undeclared via USPS commercial packages

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** all competitive commercial products (from July 2026)

**Conditions:** A HazMat Noncompliance Fee of $50 applies to any competitive commercial product when hazardous materials are detected but the customer did not appropriately declare and label them; a HazMat Handling Fee for USPS Ground Advantage is established at $0 initially.

> Also, a HazMat Noncompliance Fee of $50 will be applied to any competitive commercial product when Hazardous Materials are detected but the customer did not appropriately declare and label them.

Source: <https://www.ecommercebytes.com/2026/07/05/new-usps-noncompliance-fee-could-take-sellers-by-surprise/>

Hazardous materials shipped undeclared via USPS commercial packages — Postal shipping restrictions by item category


**Item category:** Hazardous waste, solid, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 9, NA3077, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hazardous waste, solid, n.o.s. 9 NA3077 III Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hazardous waste, solid, n.o.s. — Postal shipping restrictions by item category


**Item category:** Heating oil, light

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1202, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Heating oil, light 3 UN1202 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Heating oil, light — Postal shipping restrictions by item category


**Item category:** Helium, compressed

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.2, UN1046, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Helium, compressed 2.2 UN1046 n/a 2B 2B

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Helium, compressed — Postal shipping restrictions by item category


**Item category:** Helium, refrigerated liquid (cyrogenic liquid)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.2, UN1963, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Helium, refrigerated liquid (cyrogenic liquid) 2.2 UN1963 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Helium, refrigerated liquid (cyrogenic liquid) — Postal shipping restrictions by item category


**Item category:** hemp and hemp-based products including CBD

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail only - prohibited in international mail

**Conditions:** Hemp and hemp-based products with THC concentration not exceeding 0.3 percent are permitted domestically only when mailer complies with all applicable federal, state, and local laws; prohibited in all international mail including APO/FPO/DPO

> Hemp and hemp-based products, including cannabidiol (CBD) with the tetrahydrocannabinol (THC) concentration of such hemp (or its derivatives) not exceeding a 0.3 percent limit are permitted to be mailed domestically

Source: <https://pe.usps.com/text/pub52/pub52c4_020.htm>

hemp and hemp-based products including CBD — Postal shipping restrictions by item category


**Item category:** Hemp Products (including CBD)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic

**Conditions:** You cannot send hemp and hemp-derived products to international or military destinations.

> You cannot send hemp and hemp-derived products to international or military destinations.

Source: <https://www.usps.com/ship/shipping-restrictions.htm>

Hemp Products (including CBD) — Postal shipping restrictions by item category


**Item category:** Heptafluoropropane or Refrigerant gas R 227

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.2, UN3296, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Heptafluoropropane or Refrigerant gas R 227 2.2 UN3296 n/a 2B 2B

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Heptafluoropropane or Refrigerant gas R 227 — Postal shipping restrictions by item category


**Item category:** Heptanes

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1206, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Heptanes 3 UN1206 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Heptanes — Postal shipping restrictions by item category


**Item category:** Hexachloroacetone

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2661, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Hexachloroacetone 6.1 UN2661 III 6A 6A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexachloroacetone — Postal shipping restrictions by item category


**Item category:** Hexachlorobenzene

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2729, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Hexachlorobenzene 6.1 UN2729 III 6A 6A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexachlorobenzene — Postal shipping restrictions by item category


**Item category:** Hexachlorobutadiene

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2279, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Hexachlorobutadiene 6.1 UN2279 III 6A 6A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexachlorobutadiene — Postal shipping restrictions by item category


**Item category:** Hexachlorocyclopentadiene

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2646, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexachlorocyclopentadiene 6.1 UN2646 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexachlorocyclopentadiene — Postal shipping restrictions by item category


**Item category:** Hexachlorophene

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2875, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Hexachlorophene 6.1 UN2875 III 6A 6A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexachlorophene — Postal shipping restrictions by item category


**Item category:** Hexadecyltrichlorosilane

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1781, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexadecyltrichlorosilane 8 UN1781 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexadecyltrichlorosilane — Postal shipping restrictions by item category


**Item category:** Hexadienes

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 3, UN2458, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexadienes 3 UN2458 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexadienes — Postal shipping restrictions by item category


**Item category:** Hexaethyl tetraphosphate and compressed gas mixtures

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.3, UN1612, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexaethyl tetraphosphate and compressed gas mixtures 2.3 UN1612 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexaethyl tetraphosphate and compressed gas mixtures — Postal shipping restrictions by item category


**Item category:** Hexaethyl tetraphosphate, liquid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN1611, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexaethyl tetraphosphate, liquid 6.1 UN1611 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexaethyl tetraphosphate, liquid — Postal shipping restrictions by item category


**Item category:** Hexaethyl tetraphosphate, solid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN1611, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexaethyl tetraphosphate, solid 6.1 UN1611 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexaethyl tetraphosphate, solid — Postal shipping restrictions by item category


**Item category:** Hexafluoroacetone hydrate, liquid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2552, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexafluoroacetone hydrate, liquid 6.1 UN2552 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexafluoroacetone hydrate, liquid — Postal shipping restrictions by item category


**Item category:** Hexafluoroacetone hydrate, solid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN3436, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexafluoroacetone hydrate, solid 6.1 UN3436 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexafluoroacetone hydrate, solid — Postal shipping restrictions by item category


**Item category:** Hexafluoroacetone

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.3, UN2420, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexafluoroacetone 2.3 UN2420 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexafluoroacetone — Postal shipping restrictions by item category


**Item category:** Hexafluoroethane, compressed or Refrigerant gas R 116

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.2, UN2193, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Hexafluoroethane, compressed or Refrigerant gas R 116 2.2 UN2193 n/a 2B 2B

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexafluoroethane, compressed or Refrigerant gas R 116 — Postal shipping restrictions by item category


**Item category:** Hexafluorophosphoric acid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1782, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexafluorophosphoric acid 8 UN1782 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexafluorophosphoric acid — Postal shipping restrictions by item category


**Item category:** Hexafluoropropylene, compressed or Refrigerant gas R 1216

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.2, UN1858, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Hexafluoropropylene, compressed or Refrigerant gas R 1216 2.2 UN1858 n/a 2B 2B

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexafluoropropylene, compressed or Refrigerant gas R 1216 — Postal shipping restrictions by item category


**Item category:** Hexaldehyde

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1207, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Hexaldehyde 3 UN1207 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexaldehyde — Postal shipping restrictions by item category


**Item category:** Hexamethylene diisocyanate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2281, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexamethylene diisocyanate 6.1 UN2281 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexamethylene diisocyanate — Postal shipping restrictions by item category


**Item category:** Hexamethylene triperoxide diamine (dry)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hexamethylene triperoxide diamine (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexamethylene triperoxide diamine (dry) — Postal shipping restrictions by item category


**Item category:** Hexamethylenediamine, solid

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN2280, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Hexamethylenediamine, solid 8 UN2280 III 8A 8A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexamethylenediamine, solid — Postal shipping restrictions by item category


**Item category:** Hexamethylenediamine solution

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1783, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexamethylenediamine solution 8 UN1783 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexamethylenediamine solution — Postal shipping restrictions by item category


**Item category:** Hexamethyleneimine

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 3, UN2493, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexamethyleneimine 3 UN2493 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexamethyleneimine — Postal shipping restrictions by item category


**Item category:** Hexamethylenetetramine

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 4.1, UN1328, packing group III; domestic mail air: Prohibited; domestic mail surface: 4A

> Hexamethylenetetramine 4.1 UN1328 III Prohibited 4A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexamethylenetetramine — Postal shipping restrictions by item category


**Item category:** Hexamethylol benzene hexanitrate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hexamethylol benzene hexanitrate Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexamethylol benzene hexanitrate — Postal shipping restrictions by item category


**Item category:** Hexanes

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1208, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Hexanes 3 UN1208 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexanes — Postal shipping restrictions by item category


**Item category:** Hexanitroazoxy benzene

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hexanitroazoxy benzene Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexanitroazoxy benzene — Postal shipping restrictions by item category


**Item category:** Hexanitrodiphenyl urea

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hexanitrodiphenyl urea Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexanitrodiphenyl urea — Postal shipping restrictions by item category


**Item category:** Hexanitrodiphenylamine or Dipicrylamine or Hexyl

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 1.1D, UN0079, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexanitrodiphenylamine or Dipicrylamine or Hexyl 1.1D UN0079 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexanitrodiphenylamine or Dipicrylamine or Hexyl — Postal shipping restrictions by item category


**Item category:** Hexanitroethane

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hexanitroethane Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexanitroethane — Postal shipping restrictions by item category


**Item category:** Hexanitrooxanilide

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hexanitrooxanilide Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexanitrooxanilide — Postal shipping restrictions by item category


**Item category:** Hexanitrostilbene

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 1.1D, UN0392, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexanitrostilbene 1.1D UN0392 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexanitrostilbene — Postal shipping restrictions by item category


**Item category:** Hexanols

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2282, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Hexanols 3 UN2282 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexanols — Postal shipping restrictions by item category


**Item category:** Hexotonal

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 1.1D, UN0393, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexotonal 1.1D UN0393 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexotonal — Postal shipping restrictions by item category


**Item category:** Hexyltrichlorosilane

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1784, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hexyltrichlorosilane 8 UN1784 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hexyltrichlorosilane — Postal shipping restrictions by item category


**Item category:** HMX mixtures, wetted or desensitized RDX and HMX mixtures, wetted with not less than 15 percent water by mass or RDX and HMX mixtures, desensitized with not less than 10 percent phlegmatizer by mass

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 1.1D, UN0391, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> HMX mixtures, wetted or desensitized RDX and HMX mixtures, wetted with not less than 15 percent water by mass or RDX and HMX mixtures, desensitized with not less than 10 percent phlegmatizer by mass 1.1D UN0391 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

HMX mixtures, wetted or desensitized RDX and HMX mixtures, wetted with not less than 15 percent water by mass or RDX and HMX mixtures, desensitized with not less than 10 percent phlegmatizer by mass — Postal shipping restrictions by item category


**Item category:** honeybees

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** continental United States - surface transportation only

**Conditions:** Must be free of disease; acceptable to mail only via surface transportation; mailpieces must be plainly marked with 'Live Bees' and 'Surface Only' or 'Surface Mail Only'

> Honeybees: Acceptable to mail only via surface transportation (except for queen honeybees; refer to b.). Mailpieces must be plainly marked on the address side with "Live Bees" and "Surface Only" or "Surface Mail Only."

Source: <https://pe.usps.com/text/pub52/pub52c5_009.htm>

honeybees — Postal shipping restrictions by item category


**Item category:** Hydrazine aqueous solution, flammable with more than 37 percent hydrazine, by mass

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN3484, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrazine aqueous solution, flammable with more than 37 percent hydrazine, by mass 8 UN3484 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrazine aqueous solution, flammable with more than 37 percent hydrazine, by mass — Postal shipping restrictions by item category


**Item category:** Hydrazine aqueous solution, with more than 37 percent hydrazine, by mass

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN2030, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrazine aqueous solution, with more than 37 percent hydrazine, by mass 8 UN2030 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrazine aqueous solution, with more than 37 percent hydrazine, by mass — Postal shipping restrictions by item category


**Item category:** Hydrazine, aqueous solution with not more than 37 percent hydrazine, by mass

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN3293, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Hydrazine, aqueous solution with not more than 37 percent hydrazine, by mass 6.1 UN3293 III 6A 6A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrazine, aqueous solution with not more than 37 percent hydrazine, by mass — Postal shipping restrictions by item category


**Item category:** Hydrazine azide

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hydrazine azide Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrazine azide — Postal shipping restrictions by item category


**Item category:** Hydrazine chlorate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hydrazine chlorate Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrazine chlorate — Postal shipping restrictions by item category


**Item category:** Hydrazine decarbonic acid diazide

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hydrazine decarbonic acid diazide Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrazine decarbonic acid diazide — Postal shipping restrictions by item category


**Item category:** Hydrazine perchlorate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hydrazine perchlorate Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrazine perchlorate — Postal shipping restrictions by item category


**Item category:** Hydrazine selenate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hydrazine selenate Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrazine selenate — Postal shipping restrictions by item category


**Item category:** Hydriodic acid

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1787, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Hydriodic acid 8 UN1787 II, III 8A 8A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydriodic acid — Postal shipping restrictions by item category


**Item category:** Hydrobromic acid, with more than 49 percent hydrobromic acid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1788, packing group II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrobromic acid, with more than 49 percent hydrobromic acid 8 UN1788 II, III Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrobromic acid, with more than 49 percent hydrobromic acid — Postal shipping restrictions by item category


**Item category:** Hydrobromic acid, with not more than 49 percent hydrobromic acid

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1788, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Hydrobromic acid, with not more than 49 percent hydrobromic acid 8 UN1788 II, III 8A 8A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrobromic acid, with not more than 49 percent hydrobromic acid — Postal shipping restrictions by item category


**Item category:** Hydrocarbon gas mixture, compressed, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 2.1, UN1964, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Hydrocarbon gas mixture, compressed, n.o.s. 2.1 UN1964 n/a Prohibited 2A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrocarbon gas mixture, compressed, n.o.s. — Postal shipping restrictions by item category


**Item category:** Hydrocarbon gas mixtures, liquified, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 2.1, UN1965, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Hydrocarbon gas mixtures, liquified, n.o.s. 2.1 UN1965 n/a Prohibited 2A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrocarbon gas mixtures, liquified, n.o.s. — Postal shipping restrictions by item category


**Item category:** Hydrocarbons, liquid, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN3295, packing group I, II, III; domestic mail air: Prohibited; domestic mail surface: 3A

> Hydrocarbons, liquid, n.o.s. 3 UN3295 I, II, III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrocarbons, liquid, n.o.s. — Postal shipping restrictions by item category


**Item category:** Hydrochloric acid (UN1789)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail via air or surface transportation

**Conditions:** Acceptable only in solutions not exceeding 10% acid that qualify as Limited Quantity air or surface; Packaging Instruction 8A must be followed

> Hydrochloric Acid (UN1789): Acceptable only in solutions not exceeding 10 percent acid that qualify as Limited Quantity air or Limited Quantity surface material.

Source: <https://pe.usps.com/text/pub52/pub52c3_027.htm>

Hydrochloric acid (UN1789) — Postal shipping restrictions by item category


**Item category:** Hydrochloric acid

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1789, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Hydrochloric acid 8 UN1789 II, III 8A 8A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrochloric acid — Postal shipping restrictions by item category


**Item category:** Hydrocyanic acid, aqueous solutions with less than 5 percent hydrogen cyanide

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, NA1613, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrocyanic acid, aqueous solutions with less than 5 percent hydrogen cyanide 6.1 NA1613 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrocyanic acid, aqueous solutions with less than 5 percent hydrogen cyanide — Postal shipping restrictions by item category


**Item category:** Hydrofluoric acid and Sulfuric acid mixtures

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1786, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrofluoric acid and Sulfuric acid mixtures 8 UN1786 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrofluoric acid and Sulfuric acid mixtures — Postal shipping restrictions by item category


**Item category:** Hydrofluoric acid (UN1790)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Nonmailable corrosive

> Hydrofluoric Acid (UN1790).

Source: <https://pe.usps.com/text/pub52/pub52c3_027.htm>

Hydrofluoric acid (UN1790) — Postal shipping restrictions by item category

carrier, conditions, restriction_type, scope


**Item category:** Hydrofluoric acid, with more than 60 percent strength

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1790, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrofluoric acid, with more than 60 percent strength 8 UN1790 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrofluoric acid, with more than 60 percent strength — Postal shipping restrictions by item category


**Item category:** Hydrofluoric acid, with not more than 60 percent strength

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1790, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrofluoric acid, with not more than 60 percent strength 8 UN1790 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrofluoric acid, with not more than 60 percent strength — Postal shipping restrictions by item category


**Item category:** Hydrogen and Methane mixtures, compressed

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 2.1, UN2034, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Hydrogen and Methane mixtures, compressed 2.1 UN2034 n/a Prohibited 2A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen and Methane mixtures, compressed — Postal shipping restrictions by item category


**Item category:** Hydrogen bromide, anhydrous

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.3, UN1048, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen bromide, anhydrous 2.3 UN1048 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen bromide, anhydrous — Postal shipping restrictions by item category


**Item category:** Hydrogen chloride, anhydrous

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.3, UN1050, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen chloride, anhydrous 2.3 UN1050 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen chloride, anhydrous — Postal shipping restrictions by item category


**Item category:** Hydrogen chloride, refrigerated liquid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.3, UN2186, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen chloride, refrigerated liquid 2.3 UN2186 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen chloride, refrigerated liquid — Postal shipping restrictions by item category


**Item category:** Hydrogen, compressed

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 2.1, UN1049, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Hydrogen, compressed 2.1 UN1049 n/a Prohibited 2A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen, compressed — Postal shipping restrictions by item category


**Item category:** Hydrogen, cyanide, solution in alcohol with not more than 45 percent hydrogen cyanide

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN3294, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen, cyanide, solution in alcohol with not more than 45 percent hydrogen cyanide 6.1 UN3294 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen, cyanide, solution in alcohol with not more than 45 percent hydrogen cyanide — Postal shipping restrictions by item category


**Item category:** Hydrogen cyanide, stabilized with less than 3 percent water and absorbed in a porous inert material

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN1614, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen cyanide, stabilized with less than 3 percent water and absorbed in a porous inert material 6.1 UN1614 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen cyanide, stabilized with less than 3 percent water and absorbed in a porous inert material — Postal shipping restrictions by item category


**Item category:** Hydrogen cyanide, stabilized with less than 3 percent water

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN1051, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen cyanide, stabilized with less than 3 percent water 6.1 UN1051 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen cyanide, stabilized with less than 3 percent water — Postal shipping restrictions by item category


**Item category:** Hydrogen fluoride, anhydrous

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1052, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen fluoride, anhydrous 8 UN1052 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen fluoride, anhydrous — Postal shipping restrictions by item category


**Item category:** Hydrogen in a metal hydride storage system or Hydrogen in a metal hydride storage system contained in equipment or Hydrogen in a metal hydride storage system packed with equipment

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.1, UN3468, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen in a metal hydride storage system or Hydrogen in a metal hydride storage system contained in equipment or Hydrogen in a metal hydride storage system packed with equipment 2.1 UN3468 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen in a metal hydride storage system or Hydrogen in a metal hydride storage system contained in equipment or Hydrogen in a metal hydride storage system packed with equipment — Postal shipping restrictions by item category


**Item category:** Hydrogen iodide, anhydrous

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.3, UN2197, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen iodide, anhydrous 2.3 UN2197 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen iodide, anhydrous — Postal shipping restrictions by item category


**Item category:** Hydrogen peroxide and peroxyacetic acid mixtures, stabilized with acids, water, and not more than 5 percent peroxyacetic acid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 5.1, UN3149, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen peroxide and peroxyacetic acid mixtures, stabilized with acids, water, and not more than 5 percent peroxyacetic acid 5.1 UN3149 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen peroxide and peroxyacetic acid mixtures, stabilized with acids, water, and not more than 5 percent peroxyacetic acid — Postal shipping restrictions by item category


**Item category:** Hydrogen peroxide, aqueous solutions with more than 40 percent but not more than 60 percent hydrogen peroxide (stabilized as necessary)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 5.1, UN2014, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen peroxide, aqueous solutions with more than 40 percent but not more than 60 percent hydrogen peroxide (stabilized as necessary) 5.1 UN2014 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen peroxide, aqueous solutions with more than 40 percent but not more than 60 percent hydrogen peroxide (stabilized as necessary) — Postal shipping restrictions by item category


**Item category:** Hydrogen peroxide, aqueous solutions with not less than 20 percent but not more than 40 percent hydrogen peroxide (stabilized as necessary)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 5.1, UN2014, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen peroxide, aqueous solutions with not less than 20 percent but not more than 40 percent hydrogen peroxide (stabilized as necessary) 5.1 UN2014 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen peroxide, aqueous solutions with not less than 20 percent but not more than 40 percent hydrogen peroxide (stabilized as necessary) — Postal shipping restrictions by item category


**Item category:** Hydrogen peroxide, aqueous solutions with not less than 8 percent but less than 20 percent hydrogen peroxide (stabilized as necessary)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 5.1, UN2984, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Hydrogen peroxide, aqueous solutions with not less than 8 percent but less than 20 percent hydrogen peroxide (stabilized as necessary) 5.1 UN2984 III 5A 5A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen peroxide, aqueous solutions with not less than 8 percent but less than 20 percent hydrogen peroxide (stabilized as necessary) — Postal shipping restrictions by item category


**Item category:** Hydrogen peroxide solution (8% or less)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** all domestic mail

**Conditions:** Regulated as hazardous material but must be prepared according to DMM 601.3.4

> Hydrogen Peroxide . Division 5.1 hydrogen peroxide solutions with an 8 percent or less hydrogen peroxide content is regulated as hazardous material but must be prepared according to DMM 601.3.4.

Source: <https://pe.usps.com/text/pub52/pub52c3_024.htm>

Hydrogen peroxide solution (8% or less) — Postal shipping restrictions by item category


**Item category:** Hydrogen peroxide solution (more than 20%)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Nonmailable Division 5.1 oxidizing substance

> Hydrogen peroxide solution (more than 20 percent).

Source: <https://pe.usps.com/text/pub52/pub52c3_024.htm>

Hydrogen peroxide solution (more than 20%) — Postal shipping restrictions by item category

carrier, conditions, item_category, restriction_type, scope


**Item category:** Hydrogen peroxide solution (more than 8% but no more than 20%)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail

**Conditions:** Permitted if can qualify as Limited Quantity air or Limited Quantity surface

> Solutions of hydrogen peroxide more than 8 percent but no more than 20 percent are permitted if they can qualify as Limited Quantity air or Limited Quantity surface.

Source: <https://pe.usps.com/text/pub52/pub52c3_024.htm>

Hydrogen peroxide solution (more than 8% but no more than 20%) — Postal shipping restrictions by item category


**Item category:** Hydrogen peroxide, stabilized or Hydrogen peroxide aqueous solutions, stabilized with more than 60 percent hydrogen peroxide

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 5.1, UN2015, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen peroxide, stabilized or Hydrogen peroxide aqueous solutions, stabilized with more than 60 percent hydrogen peroxide 5.1 UN2015 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen peroxide, stabilized or Hydrogen peroxide aqueous solutions, stabilized with more than 60 percent hydrogen peroxide — Postal shipping restrictions by item category


**Item category:** Hydrogen, refrigerated liquid (cryogenic liquid)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.1, UN1966, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen, refrigerated liquid (cryogenic liquid) 2.1 UN1966 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen, refrigerated liquid (cryogenic liquid) — Postal shipping restrictions by item category


**Item category:** Hydrogen selenide, anhydrous

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.3, UN2202, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogen selenide, anhydrous 2.3 UN2202 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogen selenide, anhydrous — Postal shipping restrictions by item category


**Item category:** Hydrogendifluoride solutions, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN3471, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogendifluoride solutions, n.o.s. 8 UN3471 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogendifluoride solutions, n.o.s. — Postal shipping restrictions by item category


**Item category:** Hydrogendifluorides, n.o.s. solid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1740, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogendifluorides, n.o.s. solid 8 UN1740 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogendifluorides, n.o.s. solid — Postal shipping restrictions by item category


**Item category:** Hydrogendifluorides, n.o.s. solutions

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN3471, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Hydrogendifluorides, n.o.s. solutions 8 UN3471 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydrogendifluorides, n.o.s. solutions — Postal shipping restrictions by item category


**Item category:** Hydroxyl amine iodide

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hydroxyl amine iodide Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydroxyl amine iodide — Postal shipping restrictions by item category


**Item category:** Hydroxylamine sulfate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN2865, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Hydroxylamine sulfate 8 UN2865 III 8A 8A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hydroxylamine sulfate — Postal shipping restrictions by item category


**Item category:** Hypochlorite solutions

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1791, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Hypochlorite solutions 8 UN1791 II, III 8A 8A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hypochlorite solutions — Postal shipping restrictions by item category


**Item category:** Hypochlorites, inorganic, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 5.1, UN3212, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Hypochlorites, inorganic, n.o.s. 5.1 UN3212 II 5A 5A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hypochlorites, inorganic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Hyponitrous acid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Hyponitrous acid Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Hyponitrous acid — Postal shipping restrictions by item category


**Item category:** Igniters

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 1.1G, UN0121, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Igniters 1.1G UN0121 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Igniters — Postal shipping restrictions by item category


**Item category:** Infectious substances, affecting animals only

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.2, UN2900, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Infectious substances, affecting animals only 6.2 UN2900 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Infectious substances, affecting animals only — Postal shipping restrictions by item category


**Item category:** Infectious substances, affecting humans only

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.2, UN2814, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Infectious substances, affecting humans only 6.2 UN2814 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Infectious substances, affecting humans only — Postal shipping restrictions by item category


**Item category:** Initiating explosives (dry)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Initiating explosives (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Initiating explosives (dry) — Postal shipping restrictions by item category


**Item category:** Inks (flammable or combustible liquid)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail via surface transportation

**Conditions:** Mailable if qualify as Limited Quantity surface material and meet requirements; primary receptacles must be cushioned with absorbent material; follow Packaging Instruction 3A or 3B as applicable

> Inks: Classified as flammable or combustible liquids. Defined as colored liquids used for writing, drawing, and printing, and often composed of pigments such as carbon black suspended in a drying oil. They are mailable if they qualify as Limited Quantity surface material

Source: <https://pe.usps.com/text/pub52/pub52c3_022.htm>

Inks (flammable or combustible liquid) — Postal shipping restrictions by item category


**Item category:** Inks, stains and varnishes

**Carrier:** USPS

**Restriction type:** hazmat declaration required

**Scope:** commercial package shipments

**Conditions:** Listed by the Department of Transportation as posing a significant safety risk while being transported; $7.50 hazmat handling fee for Priority Mail; $50 noncompliance fee for packages not properly declared and labeled across all commercial packages including Ground Advantage (effective July 12 2026)

> Essential oils, nail polish (and nail polish remover), perfumes and colognes, hand sanitizer, inks, stains and varnishes, hairspray, and electronics with a lithium battery are among the products listed by the Department of Transportation as posing a significant safety risk while being transported.

Source: <https://www.ecommercebytes.com/2026/07/05/new-usps-noncompliance-fee-could-take-sellers-by-surprise/>

Inks, stains and varnishes — Postal shipping restrictions by item category


**Item category:** Inosital hexanitrate (dry)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Inosital hexanitrate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Inosital hexanitrate (dry) — Postal shipping restrictions by item category


**Item category:** Insecticide gases, flammable, n.o.s

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 2.1, UN3354, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Insecticide gases, flammable, n.o.s 2.1 UN3354 n/a Prohibited 2A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Insecticide gases, flammable, n.o.s — Postal shipping restrictions by item category


**Item category:** Insecticide gases, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.2, UN1968, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Insecticide gases, n.o.s. 2.2 UN1968 n/a 2B 2B

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Insecticide gases, n.o.s. — Postal shipping restrictions by item category


**Item category:** Insecticide gases, toxic, flammable, n.o.s., Inhalation hazard A, B, C or D

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.3, UN3355, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Insecticide gases, toxic, flammable, n.o.s., Inhalation hazard A, B, C or D 2.3 UN3355 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Insecticide gases, toxic, flammable, n.o.s., Inhalation hazard A, B, C or D — Postal shipping restrictions by item category


**Item category:** Insecticide gases, toxic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 2.3, UN1967, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Insecticide gases, toxic, n.o.s. 2.3 UN1967 n/a Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Insecticide gases, toxic, n.o.s. — Postal shipping restrictions by item category


**Item category:** intoxicating liquors - denatured flammable or combustible

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail

**Conditions:** If denaturing agents such as sodium bisulfate (a corrosive) or mercuric chloride (a poison) are used, substance must meet mailability requirements for Class 8 corrosive or Division 6.1 toxic substance; flammable or combustible contents must meet Class 3 requirements

> if denaturing agents are used, such as sodium bisulfate (a corrosive) or mercuric chloride (a poison), the substances must meet the mailability requirements for Class 8 corrosive material or a Division 6.1 toxic substance

Source: <https://pe.usps.com/text/pub52/pub52c4_006.htm>

intoxicating liquors - denatured flammable or combustible — Postal shipping restrictions by item category


**Item category:** intoxicating liquors - exempt federal/state agency mailings

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** between federal or state agency employees for official use

**Conditions:** Intoxicating liquor is exempt from the prohibition when mailed between federal or state agency employees for official use such as testing purposes

> 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).

Source: <https://pe.usps.com/text/pub52/pub52c4_006.htm>

intoxicating liquors - exempt federal/state agency mailings — Postal shipping restrictions by item category


**Item category:** intoxicating liquors - products not categorized as taxable alcoholic beverages

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** domestic mail

**Conditions:** Product must comply with IRS and FDA regulations, not be classified as a taxable alcoholic beverage, not be poisonous, and not be flammable; examples include cold remedies, cooking wine, and mouthwash

> Examples of these mailable products include cold remedies, cooking wine, and mouthwash.

Source: <https://pe.usps.com/text/pub52/pub52c4_006.htm>

intoxicating liquors - products not categorized as taxable alcoholic beverages — Postal shipping restrictions by item category


**Item category:** intoxicating liquors

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** all domestic mail

**Conditions:** Beverages with alcohol content of 0.5 percent or more by weight are taxable per Chapter 51 of the IRS Code and subject to mailability rules

> 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

Source: <https://pe.usps.com/text/pub52/pub52c4_005.htm>

intoxicating liquors — Postal shipping restrictions by item category


**Item category:** Inulin trinitrate (dry)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Inulin trinitrate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Inulin trinitrate (dry) — Postal shipping restrictions by item category


**Item category:** Iodine azide (dry)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Iodine azide (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Iodine azide (dry) — Postal shipping restrictions by item category


**Item category:** Iodine monochloride, liquid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN3498, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Iodine monochloride, liquid 8 UN3498 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Iodine monochloride, liquid — Postal shipping restrictions by item category


**Item category:** Iodine monochloride, solid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1792, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Iodine monochloride, solid 8 UN1792 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Iodine monochloride, solid — Postal shipping restrictions by item category


**Item category:** Iodine pentafluoride

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 5.1, UN2495, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Iodine pentafluoride 5.1 UN2495 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Iodine pentafluoride — Postal shipping restrictions by item category


**Item category:** Iodine

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN3495, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Iodine 8 UN3495 III Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Iodine — Postal shipping restrictions by item category


**Item category:** Iodomethylpropanes

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2391, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Iodomethylpropanes 3 UN2391 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Iodomethylpropanes — Postal shipping restrictions by item category


**Item category:** Iodopropanes

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2392, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Iodopropanes 3 UN2392 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Iodopropanes — Postal shipping restrictions by item category


**Item category:** Iodoxy compounds (dry)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Iodoxy compounds (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Iodoxy compounds (dry) — Postal shipping restrictions by item category


**Item category:** Iridium nitratopentamine iridium nitrate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Iridium nitratopentamine iridium nitrate Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Iridium nitratopentamine iridium nitrate — Postal shipping restrictions by item category


**Item category:** Iron pentacarbonyl

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN1994, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Iron pentacarbonyl 6.1 UN1994 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Iron pentacarbonyl — Postal shipping restrictions by item category


**Item category:** Irritating materials — all types

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** All irritating materials are nonmailable

> Irritating Materials: All irritating materials are nonmailable.

Source: <https://pe.usps.com/text/pub52/pub52c3_025.htm>

Irritating materials — all types — Postal shipping restrictions by item category


**Item category:** Isobutanol or Isobutyl alcohol

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1212, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isobutanol or Isobutyl alcohol 3 UN1212 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutanol or Isobutyl alcohol — Postal shipping restrictions by item category


**Item category:** Isobutyl acetate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1213, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isobutyl acetate 3 UN1213 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyl acetate — Postal shipping restrictions by item category


**Item category:** Isobutyl acrylate, stabilized

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2527, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isobutyl acrylate, stabilized 3 UN2527 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyl acrylate, stabilized — Postal shipping restrictions by item category


**Item category:** Isobutyl formate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2393, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isobutyl formate 3 UN2393 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyl formate — Postal shipping restrictions by item category


**Item category:** Isobutyl isobutyrate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2528, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isobutyl isobutyrate 3 UN2528 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyl isobutyrate — Postal shipping restrictions by item category


**Item category:** Isobutyl isocyanate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 3, UN2486, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Isobutyl isocyanate 3 UN2486 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyl isocyanate — Postal shipping restrictions by item category


**Item category:** Isobutyl methacrylate, stabilized

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2283, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isobutyl methacrylate, stabilized 3 UN2283 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyl methacrylate, stabilized — Postal shipping restrictions by item category


**Item category:** Isobutyl propionate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2394, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isobutyl propionate 3 UN2394 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyl propionate — Postal shipping restrictions by item category


**Item category:** Isobutylamine

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 3, UN1214, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Isobutylamine 3 UN1214 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutylamine — Postal shipping restrictions by item category


**Item category:** Isobutyraldehyde or Isobutyl aldehyde

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2045, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isobutyraldehyde or Isobutyl aldehyde 3 UN2045 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyraldehyde or Isobutyl aldehyde — Postal shipping restrictions by item category


**Item category:** Isobutyric acid

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2529, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isobutyric acid 3 UN2529 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyric acid — Postal shipping restrictions by item category


**Item category:** Isobutyronitrile

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 3, UN2284, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Isobutyronitrile 3 UN2284 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyronitrile — Postal shipping restrictions by item category


**Item category:** Isobutyryl chloride

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 3, UN2395, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Isobutyryl chloride 3 UN2395 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isobutyryl chloride — Postal shipping restrictions by item category


**Item category:** Isocyanates, flammable, toxic, n.o.s. or Isocyanate solutions, flammable, toxic, n.o.s. flashpoint less than 23°

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 3, UN2478, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Prohibited Isocyanates, flammable, toxic, n.o.s. or Isocyanate solutions, flammable, toxic, n.o.s. flashpoint less than 23° C 3 UN2478 II Prohibited Prohibited Isocyanates, toxic, flammable, n.o.s.

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isocyanates, flammable, toxic, n.o.s. or Isocyanate solutions, flammable, toxic, n.o.s. flashpoint less than 23° — Postal shipping restrictions by item category


**Item category:** Isocyanates, toxic, flammable, n.o.s. or Isocyanate solutions, toxic, flammable, n.o.s. flashpoint not less than 23° C but not more than 61° C and boiling point less than 300° C

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN3080, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Isocyanates, toxic, flammable, n.o.s. or Isocyanate solutions, toxic, flammable, n.o.s. flashpoint not less than 23° C but not more than 61° C and boiling point less than 300° C 6.1 UN3080 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isocyanates, toxic, flammable, n.o.s. or Isocyanate solutions, toxic, flammable, n.o.s. flashpoint not less than 23° C but not more than 61° C and boiling point less than 300° C — Postal shipping restrictions by item category


**Item category:** Isocyanates, toxic, n.o.s. or Isocyanate solutions, toxic, n.o.s. flashpoint more than 61° C and boiling point less than 300° C

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2206, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Isocyanates, toxic, n.o.s. or Isocyanate solutions, toxic, n.o.s. flashpoint more than 61° C and boiling point less than 300° C 6.1 UN2206 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isocyanates, toxic, n.o.s. or Isocyanate solutions, toxic, n.o.s. flashpoint more than 61° C and boiling point less than 300° C — Postal shipping restrictions by item category


**Item category:** Isocyanatobenzotrifluorides

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2285, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Isocyanatobenzotrifluorides 6.1 UN2285 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isocyanatobenzotrifluorides — Postal shipping restrictions by item category


**Item category:** Isoheptenes

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2287, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isoheptenes 3 UN2287 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isoheptenes — Postal shipping restrictions by item category


**Item category:** Isohexenes

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2288, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isohexenes 3 UN2288 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isohexenes — Postal shipping restrictions by item category


**Item category:** Isooctenes

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1216, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isooctenes 3 UN1216 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isooctenes — Postal shipping restrictions by item category


**Item category:** Isopentenes

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2371, packing group I; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopentenes 3 UN2371 I Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopentenes — Postal shipping restrictions by item category


**Item category:** Isophorone diisocyanate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2290, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Isophorone diisocyanate 6.1 UN2290 III 6A 6A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isophorone diisocyanate — Postal shipping restrictions by item category


**Item category:** Isophoronediamine

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN2289, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Isophoronediamine 8 UN2289 III 8A 8A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isophoronediamine — Postal shipping restrictions by item category


**Item category:** Isoprene, stabilized

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1218, packing group I; domestic mail air: Prohibited; domestic mail surface: 3A

> Isoprene, stabilized 3 UN1218 I Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isoprene, stabilized — Postal shipping restrictions by item category


**Item category:** Isopropanol or Isopropyl alcohol

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1219, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropanol or Isopropyl alcohol 3 UN1219 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropanol or Isopropyl alcohol — Postal shipping restrictions by item category


**Item category:** Isopropenyl acetate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2403, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropenyl acetate 3 UN2403 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropenyl acetate — Postal shipping restrictions by item category


**Item category:** Isopropenylbenzene

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2303, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropenylbenzene 3 UN2303 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropenylbenzene — Postal shipping restrictions by item category


**Item category:** Isopropyl 2-chloropropionate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2934, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropyl 2-chloropropionate 3 UN2934 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropyl 2-chloropropionate — Postal shipping restrictions by item category


**Item category:** Isopropyl acetate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1220, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropyl acetate 3 UN1220 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropyl acetate — Postal shipping restrictions by item category


**Item category:** Isopropyl acid phosphate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 8, UN1793, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Isopropyl acid phosphate 8 UN1793 III 8A 8A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropyl acid phosphate — Postal shipping restrictions by item category


**Item category:** Isopropyl butyrate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2405, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropyl butyrate 3 UN2405 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropyl butyrate — Postal shipping restrictions by item category


**Item category:** Isopropyl chloroacetate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2947, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropyl chloroacetate 3 UN2947 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropyl chloroacetate — Postal shipping restrictions by item category


**Item category:** Isopropyl chloroformate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 6.1, UN2407, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Isopropyl chloroformate 6.1 UN2407 I Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropyl chloroformate — Postal shipping restrictions by item category


**Item category:** Isopropyl isobutyrate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2406, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropyl isobutyrate 3 UN2406 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropyl isobutyrate — Postal shipping restrictions by item category


**Item category:** Isopropyl isocyanate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2483, packing group I; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropyl isocyanate 3 UN2483 I Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropyl isocyanate — Postal shipping restrictions by item category


**Item category:** Isopropyl nitrate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1222, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropyl nitrate 3 UN1222 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropyl nitrate — Postal shipping restrictions by item category


**Item category:** Isopropyl propionate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN2409, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropyl propionate 3 UN2409 II Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropyl propionate — Postal shipping restrictions by item category


**Item category:** Isopropylamine 3 UN1221 I Isopropylbenzene

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 3, UN1918, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isopropylamine 3 UN1221 I Isopropylbenzene 3 UN1918 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropylamine 3 UN1221 I Isopropylbenzene — Postal shipping restrictions by item category


**Item category:** Isopropylcumyl hydroperoxide, with more than 72 percent in solution

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Isopropylcumyl hydroperoxide, with more than 72 percent in solution Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isopropylcumyl hydroperoxide, with more than 72 percent in solution — Postal shipping restrictions by item category


**Item category:** Isosorbide dinitrate mixture with not less than 60 percent lactose, mannose, starch or calcium hydrogen phosphate

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Hazard class 4.1, UN2907, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Isosorbide dinitrate mixture with not less than 60 percent lactose, mannose, starch or calcium hydrogen phosphate 4.1 UN2907 II Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isosorbide dinitrate mixture with not less than 60 percent lactose, mannose, starch or calcium hydrogen phosphate — Postal shipping restrictions by item category


**Item category:** Isosorbide5mononitrate

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail: surface only (air prohibited)

**Conditions:** Hazard class 4.1, UN3251, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Isosorbide5mononitrate 4.1 UN3251 III Prohibited 3A

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isosorbide5mononitrate — Postal shipping restrictions by item category


**Item category:** Isothiocyanic acid

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail (air and surface)

**Conditions:** Listed as Forbidden in the Pub 52 Appendix A mailability guide; Prohibited in domestic mail by air and by surface.

> Isothiocyanic acid Forbidden Prohibited Prohibited Prohibited Prohibited

Source: <https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf>

Isothiocyanic acid — Postal shipping restrictions by item category


**Item category:** Items containing lithium batteries

**Carrier:** USPS

**Restriction type:** hazmat declaration required

**Scope:** seller shipments (Etsy)

**Conditions:** May have special shipping requirements under USPS hazardous materials rules; $50 noncompliance fee for undeclared or improperly prepared hazardous materials effective July 12 2026

> Some items, such as certain candles, perfumes, aerosols, nail polish, or items containing lithium batteries, may have special shipping requirements.

Source: <https://www.valueaddedresource.net/poshmark-cover-usps-hazardous-non-compliance-fee/>

Items containing lithium batteries — Postal shipping restrictions by item category