**Item category:** Chloric acid aqueous solution, with not more than 10 percent chloric acid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, UN2626, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloric acid aqueous solution, with not more than 10 percent chloric acid 5.1 UN2626 II Prohibited Prohibited

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

Chloric acid aqueous solution, with not more than 10 percent chloric acid — Postal shipping restrictions by item category


**Item category:** Chlorine 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.

> Chlorine azide Forbidden Prohibited Prohibited Prohibited Prohibited

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

Chlorine azide — Postal shipping restrictions by item category


**Item category:** Chlorine dioxide, hydrate, frozen

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, NA9191, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorine dioxide, hydrate, frozen 5.1 NA9191 II Prohibited Prohibited

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

Chlorine dioxide, hydrate, frozen — Postal shipping restrictions by item category


**Item category:** Chlorine dioxide hydrate, frozen

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Nonmailable Division 5.1 oxidizing substance

> Chlorine dioxide hydrate, frozen.

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

Chlorine dioxide hydrate, frozen — Postal shipping restrictions by item category

carrier, conditions, restriction_type, scope


**Item category:** Chlorine dioxide (not hydrate)

**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.

> Chlorine dioxide (not hydrate) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Chlorine dioxide (not hydrate) — Postal shipping restrictions by item category


**Item category:** Chlorine pentafluoride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN2548, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorine pentafluoride 2.3 UN2548 n/a Prohibited Prohibited

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

Chlorine pentafluoride — Postal shipping restrictions by item category


**Item category:** Chlorine trifluoride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1749, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorine trifluoride 2.3 UN1749 n/a Prohibited Prohibited

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

Chlorine trifluoride — Postal shipping restrictions by item category


**Item category:** Chlorite solution

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1908, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Chlorite solution 8 UN1908 II, III 8A 8A

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

Chlorite solution — Postal shipping restrictions by item category


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

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1462, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Chlorites, inorganic, n.o.s. 5.1 UN1462 II 5A 5A

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

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


**Item category:** Chloroacetic acid, molten

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3250, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroacetic acid, molten 6.1 UN3250 II Prohibited Prohibited

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

Chloroacetic acid, molten — Postal shipping restrictions by item category


**Item category:** Chloroacetic acid, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1751, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroacetic acid, solid 6.1 UN1751 II Prohibited Prohibited

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

Chloroacetic acid, solid — Postal shipping restrictions by item category


**Item category:** Chloroacetic acid, solution

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1750, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroacetic acid, solution 6.1 UN1750 II Prohibited Prohibited

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

Chloroacetic acid, solution — Postal shipping restrictions by item category


**Item category:** Chloroacetone, stabilized

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1695, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroacetone, stabilized 6.1 UN1695 I Prohibited Prohibited

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

Chloroacetone, stabilized — Postal shipping restrictions by item category


**Item category:** Chloroacetone (unstabilized)

**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.

> Chloroacetone (unstabilized) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Chloroacetone (unstabilized) — Postal shipping restrictions by item category


**Item category:** Chloroacetonitrile

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2668, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroacetonitrile 6.1 UN2668 II Prohibited Prohibited

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

Chloroacetonitrile — Postal shipping restrictions by item category


**Item category:** Chloroacetophenone (CN), liquid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3416, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroacetophenone (CN), liquid 6.1 UN3416 II Prohibited Prohibited

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

Chloroacetophenone (CN), liquid — Postal shipping restrictions by item category


**Item category:** Chloroacetophenone (CN), solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1697, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroacetophenone (CN), solid 6.1 UN1697 II Prohibited Prohibited

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

Chloroacetophenone (CN), solid — Postal shipping restrictions by item category


**Item category:** Chloroacetyl chloride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1752, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroacetyl chloride 6.1 UN1752 I Prohibited Prohibited

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

Chloroacetyl chloride — Postal shipping restrictions by item category


**Item category:** Chloroanilines, liquid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2019, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroanilines, liquid 6.1 UN2019 II Prohibited Prohibited

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

Chloroanilines, liquid — Postal shipping restrictions by item category


**Item category:** Chloroanilines, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2018, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroanilines, solid 6.1 UN2018 II Prohibited Prohibited

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

Chloroanilines, solid — Postal shipping restrictions by item category


**Item category:** Chloroanisidines

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2233, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chloroanisidines 6.1 UN2233 III 6A 6A

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

Chloroanisidines — Postal shipping restrictions by item category


**Item category:** Chlorobenzene

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1134, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Chlorobenzene 3 UN1134 III Prohibited 3A

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

Chlorobenzene — Postal shipping restrictions by item category


**Item category:** Chlorobenzotrifluorides

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2234, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Chlorobenzotrifluorides 3 UN2234 III Prohibited 3A

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

Chlorobenzotrifluorides — Postal shipping restrictions by item category


**Item category:** Chlorobenzyl chlorides, liquid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2235, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chlorobenzyl chlorides, liquid 6.1 UN2235 III 6A 6A

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

Chlorobenzyl chlorides, liquid — Postal shipping restrictions by item category


**Item category:** Chlorobenzyl chlorides, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN3427, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chlorobenzyl chlorides, solid 6.1 UN3427 III 6A 6A

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

Chlorobenzyl chlorides, solid — Postal shipping restrictions by item category


**Item category:** Chlorobutanes

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1127, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Chlorobutanes 3 UN1127 II Prohibited 3A

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

Chlorobutanes — Postal shipping restrictions by item category


**Item category:** Chlorocresols, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3437, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorocresols, solid 6.1 UN3437 II Prohibited Prohibited

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

Chlorocresols, solid — Postal shipping restrictions by item category


**Item category:** Chlorocresols, solution

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2669, packing group II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorocresols, solution 6.1 UN2669 II, III Prohibited Prohibited

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

Chlorocresols, solution — Postal shipping restrictions by item category


**Item category:** Chlorodifluorobromomethane or Refrigerant gas R 12B1

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN1974, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Chlorodifluorobromomethane or Refrigerant gas R 12B1 2.2 UN1974 n/a 2B 2B

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

Chlorodifluorobromomethane or Refrigerant gas R 12B1 — Postal shipping restrictions by item category


**Item category:** Chlorodifluoromethane and chloropentafluoroethane mixture or Refrigerant gas R 502 with fixed boiling point, with approximately 49 percent chlorodifluoromethane

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN1973, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Chlorodifluoromethane and chloropentafluoroethane mixture or Refrigerant gas R 502 with fixed boiling point, with approximately 49 percent chlorodifluoromethane 2.2 UN1973 n/a 2B 2B

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

Chlorodifluoromethane and chloropentafluoroethane mixture or Refrigerant gas R 502 with fixed boiling point, with approximately 49 percent chlorodifluoromethane — Postal shipping restrictions by item category


**Item category:** Chlorodifluoromethane or Refrigerant gas R 22

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN1018, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Chlorodifluoromethane or Refrigerant gas R 22 2.2 UN1018 n/a 2B 2B

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

Chlorodifluoromethane or Refrigerant gas R 22 — Postal shipping restrictions by item category


**Item category:** Chlorodinitrobenzenes, liquid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1577, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorodinitrobenzenes, liquid 6.1 UN1577 II Prohibited Prohibited

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

Chlorodinitrobenzenes, liquid — Postal shipping restrictions by item category


**Item category:** Chlorodinitrobenzenes, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3441, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorodinitrobenzenes, solid 6.1 UN3441 II Prohibited Prohibited

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

Chlorodinitrobenzenes, solid — Postal shipping restrictions by item category


**Item category:** Chloroform

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN1888, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chloroform 6.1 UN1888 III 6A 6A

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

Chloroform — Postal shipping restrictions by item category


**Item category:** Chloroformates, toxic, corrosive, flammable, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2742, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroformates, toxic, corrosive, flammable, n.o.s. 6.1 UN2742 II Prohibited Prohibited

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

Chloroformates, toxic, corrosive, flammable, n.o.s. — Postal shipping restrictions by item category


**Item category:** Chloroformates, toxic, corrosive, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3277, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroformates, toxic, corrosive, n.o.s. 6.1 UN3277 II Prohibited Prohibited

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

Chloroformates, toxic, corrosive, n.o.s. — Postal shipping restrictions by item category


**Item category:** Chloromethyl chloroformate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2745, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloromethyl chloroformate 6.1 UN2745 II Prohibited Prohibited

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

Chloromethyl chloroformate — Postal shipping restrictions by item category


**Item category:** Chloromethyl ethyl ether

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN2354, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloromethyl ethyl ether 3 UN2354 II Prohibited Prohibited

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

Chloromethyl ethyl ether — Postal shipping restrictions by item category


**Item category:** Chloronitroanilines

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2237, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chloronitroanilines 6.1 UN2237 III 6A 6A

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

Chloronitroanilines — Postal shipping restrictions by item category


**Item category:** Chloronitrobenzene, liquid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3409, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloronitrobenzene, liquid 6.1 UN3409 II Prohibited Prohibited

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

Chloronitrobenzene, liquid — Postal shipping restrictions by item category


**Item category:** Chloronitrobenzenes, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1578, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloronitrobenzenes, solid 6.1 UN1578 II Prohibited Prohibited

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

Chloronitrobenzenes, solid — Postal shipping restrictions by item category


**Item category:** Chloronitrotoluenes, liquid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2433, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chloronitrotoluenes, liquid 6.1 UN2433 III 6A 6A

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

Chloronitrotoluenes, liquid — Postal shipping restrictions by item category


**Item category:** Chloronitrotoluenes, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN3457, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chloronitrotoluenes, solid 6.1 UN3457 III 6A 6A

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

Chloronitrotoluenes, solid — Postal shipping restrictions by item category


**Item category:** Chloropentafluoroethane or Refrigerant gas R 115

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN1020, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Chloropentafluoroethane or Refrigerant gas R 115 2.2 UN1020 n/a 2B 2B

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

Chloropentafluoroethane or Refrigerant gas R 115 — Postal shipping restrictions by item category


**Item category:** Chlorophenolates, liquid or Phenolates, liquid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2904, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Chlorophenolates, liquid or Phenolates, liquid 8 UN2904 III 8A 8A

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

Chlorophenolates, liquid or Phenolates, liquid — Postal shipping restrictions by item category


**Item category:** Chlorophenolates, solid or Phenolates, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2905, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Chlorophenolates, solid or Phenolates, solid 8 UN2905 III 8A 8A

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

Chlorophenolates, solid or Phenolates, solid — Postal shipping restrictions by item category


**Item category:** Chlorophenols, liquid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2021, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chlorophenols, liquid 6.1 UN2021 III 6A 6A

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

Chlorophenols, liquid — Postal shipping restrictions by item category


**Item category:** Chlorophenols, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2020, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chlorophenols, solid 6.1 UN2020 III 6A 6A

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

Chlorophenols, solid — Postal shipping restrictions by item category


**Item category:** Chlorophenyltrichlorosilane

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1753, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorophenyltrichlorosilane 8 UN1753 II Prohibited Prohibited

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

Chlorophenyltrichlorosilane — Postal shipping restrictions by item category


**Item category:** Chloropicrin and methyl bromide mixtures

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1581, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloropicrin and methyl bromide mixtures 2.3 UN1581 n/a Prohibited Prohibited

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

Chloropicrin and methyl bromide mixtures — Postal shipping restrictions by item category


**Item category:** Chloropicrin and methyl chloride mixtures

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1582, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloropicrin and methyl chloride mixtures 2.3 UN1582 n/a Prohibited Prohibited

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

Chloropicrin and methyl chloride mixtures — Postal shipping restrictions by item category


**Item category:** Chloropicrin

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1580, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloropicrin 6.1 UN1580 I Prohibited Prohibited

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

Chloropicrin — Postal shipping restrictions by item category


**Item category:** Chloropivaloyl chloride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, NA9263, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloropivaloyl chloride 6.1 NA9263 I Prohibited Prohibited

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

Chloropivaloyl chloride — Postal shipping restrictions by item category


**Item category:** Chloroplatinic acid, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2507, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Chloroplatinic acid, solid 8 UN2507 III 8A 8A

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

Chloroplatinic acid, solid — Postal shipping restrictions by item category


**Item category:** Chloroprene, stabilized

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN1991, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chloroprene, stabilized 3 UN1991 I Prohibited Prohibited

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

Chloroprene, stabilized — Postal shipping restrictions by item category


**Item category:** Chloroprene, uninhibited

**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.

> Chloroprene, uninhibited Forbidden Prohibited Prohibited Prohibited Prohibited

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

Chloroprene, uninhibited — Postal shipping restrictions by item category


**Item category:** Chlorosilanes, corrosive, flammable, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2986, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorosilanes, corrosive, flammable, n.o.s. 8 UN2986 II Prohibited Prohibited

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

Chlorosilanes, corrosive, flammable, n.o.s. — Postal shipping restrictions by item category


**Item category:** Chlorosilanes, corrosive, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2987, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Chlorosilanes, corrosive, n.o.s. 8 UN2987 II 8A 8A

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

Chlorosilanes, corrosive, n.o.s. — Postal shipping restrictions by item category


**Item category:** Chlorosilanes, flammable, corrosive, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN2985, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorosilanes, flammable, corrosive, n.o.s. 3 UN2985 II Prohibited Prohibited

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

Chlorosilanes, flammable, corrosive, n.o.s. — Postal shipping restrictions by item category


**Item category:** Chlorosilanes, toxic, corrosive, flammable, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3362, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorosilanes, toxic, corrosive, flammable, n.o.s. 6.1 UN3362 II Prohibited Prohibited

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

Chlorosilanes, toxic, corrosive, flammable, n.o.s. — Postal shipping restrictions by item category


**Item category:** Chlorosilanes, toxic, corrosive, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3361, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorosilanes, toxic, corrosive, n.o.s. 6.1 UN3361 II Prohibited Prohibited

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

Chlorosilanes, toxic, corrosive, n.o.s. — Postal shipping restrictions by item category


**Item category:** Chlorosilanes, water-reactive, flammable, corrosive, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN2988, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorosilanes, water-reactive, flammable, corrosive, n.o.s. 4.3 UN2988 I Prohibited Prohibited

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

Chlorosilanes, water-reactive, flammable, corrosive, n.o.s. — Postal shipping restrictions by item category


**Item category:** Chlorosulfonic acid (with or without sulfur trioxide)

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1754, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chlorosulfonic acid (with or without sulfur trioxide) 8 UN1754 I Prohibited Prohibited

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

Chlorosulfonic acid (with or without sulfur trioxide) — Postal shipping restrictions by item category


**Item category:** Chlorotoluenes

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2238, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Chlorotoluenes 3 UN2238 III Prohibited 3A

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

Chlorotoluenes — Postal shipping restrictions by item category


**Item category:** Chlorotoluidines, liquid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN3429, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chlorotoluidines, liquid 6.1 UN3429 III 6A 6A

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

Chlorotoluidines, liquid — Postal shipping restrictions by item category


**Item category:** Chlorotoluidines, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2239, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Chlorotoluidines, solid 6.1 UN2239 III 6A 6A

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

Chlorotoluidines, solid — Postal shipping restrictions by item category


**Item category:** Chlorotrifluoromethane and trifluoromethane azeotropic mixture or Refrigerant gas R 503 with approximately 60 percent chlorotrifluoromethane

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN2599, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Chlorotrifluoromethane and trifluoromethane azeotropic mixture or Refrigerant gas R 503 with approximately 60 percent chlorotrifluoromethane 2.2 UN2599 n/a 2B 2B

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

Chlorotrifluoromethane and trifluoromethane azeotropic mixture or Refrigerant gas R 503 with approximately 60 percent chlorotrifluoromethane — Postal shipping restrictions by item category


**Item category:** Chlorotrifluoromethane or Refrigerant gas R 13

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN1022, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Chlorotrifluoromethane or Refrigerant gas R 13 2.2 UN1022 n/a 2B 2B

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

Chlorotrifluoromethane or Refrigerant gas R 13 — Postal shipping restrictions by item category


**Item category:** Chromic acid, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, NA1463, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chromic acid, solid 5.1 NA1463 II Prohibited Prohibited

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

Chromic acid, solid — Postal shipping restrictions by item category


**Item category:** Chromic acid solution

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1755, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Chromic acid solution 8 UN1755 II, III 8A 8A

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

Chromic acid solution — Postal shipping restrictions by item category


**Item category:** Chromic fluoride, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1756, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Chromic fluoride, solid 8 UN1756 II 8A 8A

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

Chromic fluoride, solid — Postal shipping restrictions by item category


**Item category:** Chromic fluoride, solution

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1757, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Chromic fluoride, solution 8 UN1757 II, III 8A 8A

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

Chromic fluoride, solution — Postal shipping restrictions by item category


**Item category:** Chromium nitrate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN2720, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Chromium nitrate 5.1 UN2720 III 5A 5A

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

Chromium nitrate — Postal shipping restrictions by item category


**Item category:** Chromium oxychloride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1758, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chromium oxychloride 8 UN1758 I Prohibited Prohibited

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

Chromium oxychloride — Postal shipping restrictions by item category


**Item category:** Chromium trioxide, anhydrous

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, UN1463, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chromium trioxide, anhydrous 5.1 UN1463 II Prohibited Prohibited

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

Chromium trioxide, anhydrous — Postal shipping restrictions by item category


**Item category:** Chromosulfuric acid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2240, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Chromosulfuric acid 8 UN2240 I Prohibited Prohibited

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

Chromosulfuric acid — Postal shipping restrictions by item category


**Item category:** Cigarette lighters charged with fuel (NA1057)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Lighters charged with fuel and having an ignition system are nonmailable; may seek DOT approval number for mailability ruling

> Cigarette Lighters (NA1057): Generally classified as Class 3 flammable liquid, lighters charged with fuel and having an ignition system (or similar heating, lighting, or ignition device) are nonmailable.

Source: <https://pe.usps.com/text/pub52/pub52c3_021.htm>

Cigarette lighters charged with fuel (NA1057) — Postal shipping restrictions by item category


**Item category:** Cigarettes, Cigars, & Tobacco

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic

**Conditions:** Cigarettes and smokeless tobacco are restricted items and can only be mailed in limited circumstances. Cigars may be mailed domestically.

> Cigarettes and smokeless tobacco are restricted items and can only be mailed in limited circumstances. Cigars may be mailed domestically.

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

Cigarettes, Cigars, & Tobacco — Postal shipping restrictions by item category


**Item category:** cigarettes

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** all domestic mail

**Conditions:** Any roll of tobacco wrapped in paper or any substance not containing tobacco, or roll of tobacco wrapped in substance containing tobacco likely to be purchased as a cigarette; includes roll-your-own tobacco, excludes cigars

> Any roll of tobacco wrapped in paper or in any substance not containing tobacco, or a roll of tobacco wrapped in any substance containing tobacco that, due to its appearance, the type of tobacco used in the filler, or its packaging and labeling, is likely to be offered to, or purchased by, consumers as a cigarette.

Source: <https://pe.usps.com/text/pub52/pub52c4_026.htm>

cigarettes — Postal shipping restrictions by item category

carrier, conditions, item_category, scope


**Item category:** Cleaning agents and solvents (flammable liquid)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail via surface transportation

**Conditions:** Mailable if qualifies as Limited Quantity surface material and meets conditions; Packaging Instruction 3A must be followed

> Cleaning Agents and Solvents: A flammable liquid. It is mailable if it qualifies as Limited Quantity surface materials and meet the conditions in 343.21 as applicable.

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

Cleaning agents and solvents (flammable liquid) — Postal shipping restrictions by item category


**Item category:** Coal briquettes, hot

**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.

> Coal briquettes, hot Forbidden Prohibited Prohibited Prohibited Prohibited

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

Coal briquettes, hot — Postal shipping restrictions by item category


**Item category:** Coal gas, compressed

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1023, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Coal gas, compressed 2.3 UN1023 n/a Prohibited Prohibited

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

Coal gas, compressed — Postal shipping restrictions by item category


**Item category:** Coal tar distillates, flammable

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1136, packing group II, III; domestic mail air: Prohibited; domestic mail surface: 3A

> Coal tar distillates, flammable 3 UN1136 II, III Prohibited 3A

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

Coal tar distillates, flammable — Postal shipping restrictions by item category


**Item category:** Coating solution (includes surface treatments or coatings used for industrial or other purposes such as vehicle undercoating, drum or barrel lining)

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1139, packing group I, II, III; domestic mail air: Prohibited; domestic mail surface: 3A

> Coating solution (includes surface treatments or coatings used for industrial or other purposes such as vehicle undercoating, drum or barrel lining) 3 UN1139 I, II, III Prohibited 3A

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

Coating solution (includes surface treatments or coatings used for industrial or other purposes such as vehicle undercoating, drum or barrel lining) — Postal shipping restrictions by item category


**Item category:** Cobalt naphthenates, powder

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.1, UN2001, packing group III; domestic mail air: Prohibited; domestic mail surface: 4A

> Cobalt naphthenates, powder 4.1 UN2001 III Prohibited 4A

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

Cobalt naphthenates, powder — Postal shipping restrictions by item category


**Item category:** Cobalt resinate, precipitated

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.1, UN1318, packing group III; domestic mail air: Prohibited; domestic mail surface: 4A

> Cobalt resinate, precipitated 4.1 UN1318 III Prohibited 4A

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

Cobalt resinate, precipitated — Postal shipping restrictions by item category


**Item category:** Coke, hot

**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.

> Coke, hot Forbidden Prohibited Prohibited Prohibited Prohibited

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

Coke, hot — Postal shipping restrictions by item category


**Item category:** Combustible liquids — domestic air

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail via air transportation

**Conditions:** Mailable if qualify as ID8000 materials and meet criteria; Packaging Instruction 3B must be followed

> Domestic Mail via Air Transportation: Combustible liquids are mailable if they qualify as ID8000 materials

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

Combustible liquids — domestic air — Postal shipping restrictions by item category


**Item category:** Combustible liquids — domestic surface

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail via surface transportation

**Conditions:** Mailable if qualify as Limited Quantity and consumer commodity materials and meet criteria; Packaging Instruction 3B must be followed

> Domestic Mail via Surface Transportation: Combustible liquids are mailable if they qualify as Limited Quantity and consumer commodity materials

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

Combustible liquids — domestic surface — Postal shipping restrictions by item category

carrier, conditions, item_category, restriction_type


**Item category:** Combustible Liquids (Hazard Class 3)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** Domestic Mail via Air Transportation (as ID8000) or Surface Transportation (as Limited Quantity); prohibited International

**Conditions:** Via air, mailable if they qualify as ID8000 materials per 335 and meet criteria in Exhibit 343.22. Via surface, mailable if they qualify as Limited Quantity and consumer commodity materials per 343.22. Prohibited in international mail.

> //pe.usps.com/text/pub52/pub52c3_022.htm> 343 Flammable and Combustible Liquids (Hazard Class 3) <https://pe.usps.com/text/pub52/pub52c3_023.htm> 344 Flammable Solids (Hazard Class 4) <https://pe.usps.com/text/pub52/pub52c3_024.htm> 345 Oxidizing Substances, Organic Peroxides (Hazard Class 5) <https://pe.usps.com/text/pub52/pub52c3_025.htm> 346 Toxic Substan

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

Combustible Liquids (Hazard Class 3) — Postal shipping restrictions by item category


**Item category:** Combustible liquids — international mail

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** international mail

**Conditions:** All combustible liquids are prohibited from international mail

> International Mail: Combustible liquids are prohibited.

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

Combustible liquids — international mail — Postal shipping restrictions by item category


**Item category:** Commercial parcels — USPS Hazmat Quality compliance category

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** all commercial parcels (from July 12, 2026)

**Conditions:** USPS created a Hazmat Quality (HQ) compliance category with a 100 percent compliance threshold; failing any threshold results in the Package Quality Noncompliance Fee or the Hazmat Noncompliance Fee, whichever is higher.

> USPS is creating a new compliance category called "Hazmat Quality" (HQ) with a 100 percent compliance threshold — meaning zero tolerance.

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

Commercial parcels — USPS Hazmat Quality compliance category — Postal shipping restrictions by item category


**Item category:** Common household dry-cell batteries (AA, AAA, C, D, etc.)

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** all mail

**Conditions:** Generally not regulated as hazardous materials; mailable subject to DMM 601 packaging requirements

> Household Dry-Cell Batteries: Common household battery types (AA, AAA, C, D, etc.) are generally not regulated as hazardous materials and are mailable.

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

Common household dry-cell batteries (AA, AAA, C, D, etc.) — Postal shipping restrictions by item category


**Item category:** Compact fluorescent lamps and similar devices with small amounts of mercury (UN3506)

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Mailable if each device contains 100 mg or less of mercury and each mailpiece contains no more than 1 gram of mercury total; follow Packaging Instruction 8C

> Manufactured devices that contain small amounts of mercury (UN3506): Compact Fluorescent Lamps (CFL) and similar consumer devices containing minute amounts of mercury are mailable by air or surface only when each device, article, or apparatus contains 100 milligrams (mg) (0.0035 ounce) or less of mercury

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

Compact fluorescent lamps and similar devices with small amounts of mercury (UN3506) — Postal shipping restrictions by item category


**Item category:** Components, explosive train, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.2B, UN0382, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Components, explosive train, n.o.s. 1.2B UN0382 II Prohibited Prohibited

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

Components, explosive train, n.o.s. — Postal shipping restrictions by item category


**Item category:** Compounds, cleaning liquid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, NA1760, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Compounds, cleaning liquid 8 NA1760 II, III 8A 8A

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

Compounds, cleaning liquid — Postal shipping restrictions by item category


**Item category:** Compounds, tree killing liquid or Compounds, weed killing, liquid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, NA1993, packing group I, II, III; domestic mail air: Prohibited; domestic mail surface: 3A

> Compounds, tree killing liquid or Compounds, weed killing, liquid 3 NA1993 I, II, III Prohibited 3A

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

Compounds, tree killing liquid or Compounds, weed killing, liquid — Postal shipping restrictions by item category


**Item category:** Compressed gas, flammable, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN1954, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Compressed gas, flammable, n.o.s. 2.1 UN1954 n/a Prohibited 2A

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

Compressed gas, flammable, n.o.s. — Postal shipping restrictions by item category


**Item category:** Compressed gas, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN1956, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Compressed gas, n.o.s. 2.2 UN1956 n/a 2B 2B

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

Compressed gas, n.o.s. — Postal shipping restrictions by item category


**Item category:** Compressed gas, oxidizing, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN3156, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Compressed gas, oxidizing, n.o.s. 2.2 UN3156 n/a 2B 2B

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

Compressed gas, oxidizing, n.o.s. — Postal shipping restrictions by item category


**Item category:** Compressed gas, toxic, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN3304, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Compressed gas, toxic, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN3304 n/a Prohibited Prohibited

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

Compressed gas, toxic, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D — Postal shipping restrictions by item category


**Item category:** Compressed gas, toxic, flammable, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN3305, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Compressed gas, toxic, flammable, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN3305 n/a Prohibited Prohibited

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

Compressed gas, toxic, flammable, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D — Postal shipping restrictions by item category


**Item category:** Compressed gas, toxic, flammable, n.o.s. Inhalation Hazard Zone A, B, C, or D

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1953, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Compressed gas, toxic, flammable, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN1953 n/a Prohibited Prohibited

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

Compressed gas, toxic, flammable, n.o.s. Inhalation Hazard Zone A, B, C, or D — Postal shipping restrictions by item category


**Item category:** Compressed gas, toxic, n.o.s. Inhalation Hazard Zone A, B, C, or D

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1955, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Compressed gas, toxic, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN1955 n/a Prohibited Prohibited

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

Compressed gas, toxic, n.o.s. Inhalation Hazard Zone A, B, C, or D — Postal shipping restrictions by item category


**Item category:** Compressed gas, toxic, oxidizing, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN3306, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Compressed gas, toxic, oxidizing, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN3306 n/a Prohibited Prohibited

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

Compressed gas, toxic, oxidizing, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D — Postal shipping restrictions by item category


**Item category:** Compressed gas, toxic, oxidizing, n.o.s. Inhalation Hazard Zone A, B, C, or D

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN3303, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Compressed gas, toxic, oxidizing, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN3303 n/a Prohibited Prohibited

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

Compressed gas, toxic, oxidizing, n.o.s. Inhalation Hazard Zone A, B, C, or D — Postal shipping restrictions by item category


**Item category:** Contrivances, water-activated, with burster, expelling charge, or propelling charge

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.3L, UN0249, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Contrivances, water-activated, with burster, expelling charge, or propelling charge 1.3L UN0249 II Prohibited Prohibited

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

Contrivances, water-activated, with burster, expelling charge, or propelling charge — Postal shipping restrictions by item category


**Item category:** controlled substances - DEA-registered mailers

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** domestic mail - between DEA-registered parties

**Conditions:** Controlled substances are acceptable in domestic mail only when both mailer and addressee are registered with DEA or are exempted from DEA registration such as military, civil defense, and law enforcement personnel performing official duties

> Controlled substances, and drugs that contain controlled substances, are acceptable in the domestic mail only under the following conditions:

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

controlled substances - DEA-registered mailers — Postal shipping restrictions by item category


**Item category:** controlled substances - Schedule I-V

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail - when distribution is unlawful

**Conditions:** If the distribution of a controlled substance is unlawful under 21 U.S.C. Section 801-971 or implementing regulations, mailing is also unlawful under 18 U.S.C. Section 1716

> the mailing of the substance is also unlawful under 18 U.S.C. § 1716.

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

controlled substances - Schedule I-V — Postal shipping restrictions by item category


**Item category:** Copper acetoarsenite

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1585, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Copper acetoarsenite 6.1 UN1585 II Prohibited Prohibited

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

Copper acetoarsenite — Postal shipping restrictions by item category


**Item category:** Copper acetylide

**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.

> Copper acetylide Forbidden Prohibited Prohibited Prohibited Prohibited

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

Copper acetylide — Postal shipping restrictions by item category


**Item category:** Copper amine 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.

> Copper amine azide Forbidden Prohibited Prohibited Prohibited Prohibited

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

Copper amine azide — Postal shipping restrictions by item category


**Item category:** Copper arsenite

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1586, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Copper arsenite 6.1 UN1586 II Prohibited Prohibited

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

Copper arsenite — Postal shipping restrictions by item category


**Item category:** Copper based pesticides, liquid, flammable, toxic, flashpoint less than 23° C

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN2776, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Copper based pesticides, liquid, flammable, toxic, flashpoint less than 23° C 3 UN2776 I, II Prohibited Prohibited

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

Copper based pesticides, liquid, flammable, toxic, flashpoint less than 23° C — Postal shipping restrictions by item category


**Item category:** Copper based pesticides, liquid, toxic, flammable, flashpoint not less than 23° C

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3009, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Copper based pesticides, liquid, toxic, flammable, flashpoint not less than 23° C 6.1 UN3009 I, II Prohibited Prohibited

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

Copper based pesticides, liquid, toxic, flammable, flashpoint not less than 23° C — Postal shipping restrictions by item category


**Item category:** Copper based pesticides, liquid, toxic

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3010, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Copper based pesticides, liquid, toxic 6.1 UN3010 I, II Prohibited Prohibited

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

Copper based pesticides, liquid, toxic — Postal shipping restrictions by item category


**Item category:** Copper based pesticides, solid, toxic

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2775, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Copper based pesticides, solid, toxic 6.1 UN2775 I, II Prohibited Prohibited

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

Copper based pesticides, solid, toxic — Postal shipping restrictions by item category


**Item category:** Copper chlorate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN2721, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Copper chlorate 5.1 UN2721 II 5A 5A

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

Copper chlorate — Postal shipping restrictions by item category


**Item category:** Copper chloride

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2802, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Copper chloride 8 UN2802 III 8A 8A

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

Copper chloride — Postal shipping restrictions by item category


**Item category:** Copper cyanide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1587, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Copper cyanide 6.1 UN1587 II Prohibited Prohibited

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

Copper cyanide — Postal shipping restrictions by item category


**Item category:** Copper tetramine 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.

> Copper tetramine nitrate Forbidden Prohibited Prohibited Prohibited Prohibited

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

Copper tetramine nitrate — Postal shipping restrictions by item category


**Item category:** Copra

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN1363, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Copra 4.2 UN1363 III Prohibited Prohibited

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

Copra — Postal shipping restrictions by item category


**Item category:** Cord, detonating, flexible

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1D, UN0065, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cord, detonating, flexible 1.1D UN0065 II Prohibited Prohibited

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

Cord, detonating, flexible — Postal shipping restrictions by item category


**Item category:** Cord, detonating, mild effect or Fuse, detonating, mild effect metal clad

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.4D, UN0104, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cord, detonating, mild effect or Fuse, detonating, mild effect metal clad 1.4D UN0104 II Prohibited Prohibited

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

Cord, detonating, mild effect or Fuse, detonating, mild effect metal clad — Postal shipping restrictions by item category


**Item category:** Cord detonating or Fuse detonating metal clad

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.2D, UN0102, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cord detonating or Fuse detonating metal clad 1.2D UN0102 II Prohibited Prohibited

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

Cord detonating or Fuse detonating metal clad — Postal shipping restrictions by item category


**Item category:** Cord, igniter

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.4G, UN0066, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cord, igniter 1.4G UN0066 II Prohibited Prohibited

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

Cord, igniter — Postal shipping restrictions by item category


**Item category:** Corrosive liquid, acidic, inorganic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3264, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive liquid, acidic, inorganic, n.o.s. 8 UN3264 I Prohibited Prohibited

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

Corrosive liquid, acidic, inorganic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive liquid, acidic, organic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3265, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive liquid, acidic, organic, n.o.s. 8 UN3265 I Prohibited Prohibited

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

Corrosive liquid, acidic, organic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive liquid, basic, inorganic, n.o.s

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN3266, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Corrosive liquid, basic, inorganic, n.o.s 8 UN3266 II, III 8A 8A

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

Corrosive liquid, basic, inorganic, n.o.s — Postal shipping restrictions by item category


**Item category:** Corrosive liquid, basic, organic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3267, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive liquid, basic, organic, n.o.s. 8 UN3267 I Prohibited Prohibited

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

Corrosive liquid, basic, organic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive liquid mixtures qualifying as Limited Quantity — domestic

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Mailable if 1 pint or less and contains 15% or less corrosive material; must meet Limited Quantity requirements

> Domestic Mail: Corrosive materials may be mailable if they meet Limited Quantity requirements for air or surface transportation

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

Corrosive liquid mixtures qualifying as Limited Quantity — domestic — Postal shipping restrictions by item category


**Item category:** Corrosive liquids, flammable, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2920, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive liquids, flammable, n.o.s. 8 UN2920 I, II Prohibited Prohibited

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

Corrosive liquids, flammable, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive liquids, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1760, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive liquids, n.o.s. 8 UN1760 I Prohibited Prohibited

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

Corrosive liquids, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive liquids, oxidizing, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3093, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive liquids, oxidizing, n.o.s. 8 UN3093 I, II Prohibited Prohibited

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

Corrosive liquids, oxidizing, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive liquids, self-heating, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3301, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive liquids, self-heating, n.o.s. 8 UN3301 I Prohibited Prohibited

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

Corrosive liquids, self-heating, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive liquids, toxic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2922, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive liquids, toxic, n.o.s. 8 UN2922 I, II Prohibited Prohibited

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

Corrosive liquids, toxic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive liquids, water-reactive, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3094, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive liquids, water-reactive, n.o.s. 8 UN3094 I, II Prohibited Prohibited

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

Corrosive liquids, water-reactive, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive solid, acidic, inorganic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3260, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive solid, acidic, inorganic, n.o.s. 8 UN3260 I Prohibited Prohibited

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

Corrosive solid, acidic, inorganic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive solid, acidic, organic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3261, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive solid, acidic, organic, n.o.s. 8 UN3261 I Prohibited Prohibited

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

Corrosive solid, acidic, organic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive solid, basic, inorganic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3262, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive solid, basic, inorganic, n.o.s. 8 UN3262 I Prohibited Prohibited

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

Corrosive solid, basic, inorganic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive solid, basic, organic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3263, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive solid, basic, organic, n.o.s. 8 UN3263 I Prohibited Prohibited

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

Corrosive solid, basic, organic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive solids, flammable, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2921, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive solids, flammable, n.o.s. 8 UN2921 I, II Prohibited Prohibited

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

Corrosive solids, flammable, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive solids, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1759, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive solids, n.o.s. 8 UN1759 I Prohibited Prohibited

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

Corrosive solids, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive solids, oxidizing, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3084, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive solids, oxidizing, n.o.s. 8 UN3084 I, II Prohibited Prohibited

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

Corrosive solids, oxidizing, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive solids, self-heating, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3095, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive solids, self-heating, n.o.s. 8 UN3095 I, II Prohibited Prohibited

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

Corrosive solids, self-heating, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive solids, toxic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2923, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive solids, toxic, n.o.s. 8 UN2923 I, II Prohibited Prohibited

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

Corrosive solids, toxic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosive solids, water-reactive, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3096, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Corrosive solids, water-reactive, n.o.s. 8 UN3096 I, II Prohibited Prohibited

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

Corrosive solids, water-reactive, n.o.s. — Postal shipping restrictions by item category


**Item category:** Corrosives (Hazard Class 8) — international mail

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** international mail

**Conditions:** All corrosives are prohibited from international mail

> International Mail: All corrosives are prohibited.

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

Corrosives (Hazard Class 8) — international mail — Postal shipping restrictions by item category


**Item category:** Cotton waste, oily

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN1364, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cotton waste, oily 4.2 UN1364 III Prohibited Prohibited

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

Cotton waste, oily — Postal shipping restrictions by item category


**Item category:** Cotton, wet

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN1365, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cotton, wet 4.2 UN1365 III Prohibited Prohibited

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

Cotton, wet — Postal shipping restrictions by item category


**Item category:** Cotton

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 9, NA1365, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cotton 9 NA1365 n/a Prohibited Prohibited

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

Cotton — Postal shipping restrictions by item category


**Item category:** Coumarin derivative pesticides, liquid, flammable, toxic, flashpoint less than 23° C

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN3024, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Coumarin derivative pesticides, liquid, flammable, toxic, flashpoint less than 23° C 3 UN3024 I, II Prohibited Prohibited

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

Coumarin derivative pesticides, liquid, flammable, toxic, flashpoint less than 23° C — Postal shipping restrictions by item category


**Item category:** Coumarin derivative pesticides, liquid, toxic, flammable, flashpoint not less than 23° C

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3025, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Coumarin derivative pesticides, liquid, toxic, flammable, flashpoint not less than 23° C 6.1 UN3025 I, II Prohibited Prohibited

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

Coumarin derivative pesticides, liquid, toxic, flammable, flashpoint not less than 23° C — Postal shipping restrictions by item category


**Item category:** Coumarin derivative pesticides, liquid, toxic

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3026, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Coumarin derivative pesticides, liquid, toxic 6.1 UN3026 I, II Prohibited Prohibited

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

Coumarin derivative pesticides, liquid, toxic — Postal shipping restrictions by item category


**Item category:** Coumarin derivative pesticides, solid, toxic

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3027, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Coumarin derivative pesticides, solid, toxic 6.1 UN3027 I, II Prohibited Prohibited

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

Coumarin derivative pesticides, solid, toxic — Postal shipping restrictions by item category


**Item category:** covered products (cigarettes, smokeless tobacco, ENDS) - general prohibition

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail - general public

**Conditions:** The Postal Service will not accept, forward, or deliver packages it knows or reasonably believes to contain nonmailable covered products; seized and forfeited nonmailable covered products will be destroyed

> The Postal Service will not accept, forward, or deliver packages it knows, or reasonably believes, to contain nonmailable covered products.

Source: <https://pe.usps.com/text/pub52/pub52c4_027.htm>

covered products (cigarettes, smokeless tobacco, ENDS) - general prohibition — Postal shipping restrictions by item category


**Item category:** covered products - seizure and forfeiture

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Nonmailable covered products deposited in the mail are subject to seizure and forfeiture; will be destroyed or retained by the federal government for crime detection, prosecution, or related investigations

> Nonmailable covered products deposited in the mail are subject to seizure and forfeiture.

Source: <https://pe.usps.com/text/pub52/pub52c4_027.htm>

covered products - seizure and forfeiture — Postal shipping restrictions by item category


**Item category:** Cremated Remains

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** Domestic via Priority Mail Express only; International via Priority Mail Express International only when destination country permits

**Conditions:** Domestic: Must be sent via Priority Mail Express service using USPS-produced cremated remains packaging (BOX-CRE). International: Only through Priority Mail Express International in BOX-CRE packaging when the destination country permits. Must verify destination country accepts both service and cremated remains.

> on <https://pe.usps.com/text/pub52/pub52apxc_036.htm> 10C - Cremated Remains <https://pe.usps.com/text/pub52/pub52apxc_037.htm> 10D - Adult Bird Boxes <https://pe.usps.com/text/pub52/pub52apxd.htm> Appendix D <https://pe.usps.com/text/pub52/pub52apxe_001.htm> Appendix E <https://pe.usps.com/text/pub52/pub52apxe_002.htm> Postal Service Publications and Refere

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

Cremated Remains — Postal shipping restrictions by item category


**Item category:** Cremated Remains

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** domestic

**Conditions:** Other Guidelines on Shipping & Packaging Cremated Remains

> Other Guidelines on Shipping & Packaging Cremated Remains

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


**Item category:** Cresols, liquid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2076, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cresols, liquid 6.1 UN2076 II Prohibited Prohibited

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

Cresols, liquid — Postal shipping restrictions by item category


**Item category:** Cresols, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3455, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cresols, solid 6.1 UN3455 II Prohibited Prohibited

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

Cresols, solid — Postal shipping restrictions by item category


**Item category:** Cresylic acid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2022, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cresylic acid 6.1 UN2022 II Prohibited Prohibited

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

Cresylic acid — Postal shipping restrictions by item category


**Item category:** Crotonaldehyde or Crotonaldehyde, stabilized

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1143, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Crotonaldehyde or Crotonaldehyde, stabilized 6.1 UN1143 I Prohibited Prohibited

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

Crotonaldehyde or Crotonaldehyde, stabilized — Postal shipping restrictions by item category


**Item category:** Crotonic acid, liquid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN3472, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Crotonic acid, liquid 8 UN3472 III 8A 8A

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

Crotonic acid, liquid — Postal shipping restrictions by item category


**Item category:** Crotonic acid, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2823, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Crotonic acid, solid 8 UN2823 III 8A 8A

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

Crotonic acid, solid — Postal shipping restrictions by item category


**Item category:** Crotonylene

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1144, packing group I; domestic mail air: Prohibited; domestic mail surface: 3A

> Crotonylene 3 UN1144 I Prohibited 3A

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

Crotonylene — Postal shipping restrictions by item category


**Item category:** Cupriethylenediamine solution

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1761, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cupriethylenediamine solution 8 UN1761 II Prohibited Prohibited

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

Cupriethylenediamine solution — Postal shipping restrictions by item category


**Item category:** Cutters, cable, explosive

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.4S, UN0070, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cutters, cable, explosive 1.4S UN0070 II Prohibited Prohibited

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

Cutters, cable, explosive — Postal shipping restrictions by item category


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

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1935, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyanide solutions, n.o.s. 6.1 UN1935 I, II Prohibited Prohibited

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

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


**Item category:** Cyanides, inorganic, solid, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1588, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyanides, inorganic, solid, n.o.s. 6.1 UN1588 I, II Prohibited Prohibited

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

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


**Item category:** Cyanogen bromide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1889, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyanogen bromide 6.1 UN1889 I Prohibited Prohibited

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

Cyanogen bromide — Postal shipping restrictions by item category


**Item category:** Cyanogen chloride, stabilized

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1589, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyanogen chloride, stabilized 2.3 UN1589 n/a Prohibited Prohibited

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

Cyanogen chloride, stabilized — Postal shipping restrictions by item category


**Item category:** Cyanogen

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1026, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyanogen 2.3 UN1026 n/a Prohibited Prohibited

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

Cyanogen — Postal shipping restrictions by item category


**Item category:** Cyanuric chloride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2670, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyanuric chloride 8 UN2670 II Prohibited Prohibited

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

Cyanuric chloride — Postal shipping restrictions by item category


**Item category:** Cyanuric triazide

**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.

> Cyanuric triazide Forbidden Prohibited Prohibited Prohibited Prohibited

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

Cyanuric triazide — Postal shipping restrictions by item category


**Item category:** Cyclobutane

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN2601, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Cyclobutane 2.1 UN2601 n/a Prohibited 2A

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

Cyclobutane — Postal shipping restrictions by item category


**Item category:** Cyclobutyl chloroformate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2744, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyclobutyl chloroformate 6.1 UN2744 II Prohibited Prohibited

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

Cyclobutyl chloroformate — Postal shipping restrictions by item category


**Item category:** Cycloheptane

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2241, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Cycloheptane 3 UN2241 II Prohibited 3A

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

Cycloheptane — Postal shipping restrictions by item category


**Item category:** Cycloheptatriene

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN2603, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cycloheptatriene 3 UN2603 II Prohibited Prohibited

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

Cycloheptatriene — Postal shipping restrictions by item category


**Item category:** Cycloheptene

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2242, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Cycloheptene 3 UN2242 II Prohibited 3A

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

Cycloheptene — Postal shipping restrictions by item category


**Item category:** Cyclohexane

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1145, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclohexane 3 UN1145 II Prohibited 3A

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

Cyclohexane — Postal shipping restrictions by item category


**Item category:** Cyclohexanone

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1915, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclohexanone 3 UN1915 III Prohibited 3A

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

Cyclohexanone — Postal shipping restrictions by item category


**Item category:** Cyclohexene

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2256, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclohexene 3 UN2256 II Prohibited 3A

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

Cyclohexene — Postal shipping restrictions by item category


**Item category:** Cyclohexenyltrichlorosilane

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1762, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyclohexenyltrichlorosilane 8 UN1762 II Prohibited Prohibited

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

Cyclohexenyltrichlorosilane — Postal shipping restrictions by item category


**Item category:** Cyclohexyl acetate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2243, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclohexyl acetate 3 UN2243 III Prohibited 3A

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

Cyclohexyl acetate — Postal shipping restrictions by item category


**Item category:** Cyclohexyl isocyanate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2488, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyclohexyl isocyanate 6.1 UN2488 I Prohibited Prohibited

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

Cyclohexyl isocyanate — Postal shipping restrictions by item category


**Item category:** Cyclohexyl mercaptan

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN3054, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclohexyl mercaptan 3 UN3054 III Prohibited 3A

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

Cyclohexyl mercaptan — Postal shipping restrictions by item category


**Item category:** Cyclohexylamine

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2357, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyclohexylamine 8 UN2357 II Prohibited Prohibited

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

Cyclohexylamine — Postal shipping restrictions by item category


**Item category:** Cyclohexyltrichlorosilane

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1763, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Cyclohexyltrichlorosilane 8 UN1763 II Prohibited Prohibited

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

Cyclohexyltrichlorosilane — Postal shipping restrictions by item category


**Item category:** Cyclooctadienes

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2520, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclooctadienes 3 UN2520 III Prohibited 3A

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

Cyclooctadienes — Postal shipping restrictions by item category


**Item category:** Cyclooctatetraene

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2358, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclooctatetraene 3 UN2358 II Prohibited 3A

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

Cyclooctatetraene — Postal shipping restrictions by item category


**Item category:** Cyclopentane

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1146, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclopentane 3 UN1146 II Prohibited 3A

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

Cyclopentane — Postal shipping restrictions by item category


**Item category:** Cyclopentanol

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2244, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclopentanol 3 UN2244 III Prohibited 3A

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

Cyclopentanol — Postal shipping restrictions by item category


**Item category:** Cyclopentanone

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2245, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclopentanone 3 UN2245 III Prohibited 3A

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

Cyclopentanone — Postal shipping restrictions by item category


**Item category:** Cyclopentene

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2246, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Cyclopentene 3 UN2246 II Prohibited 3A

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

Cyclopentene — Postal shipping restrictions by item category


**Item category:** Cyclopropane

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN1027, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Cyclopropane 2.1 UN1027 n/a Prohibited 2A

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

Cyclopropane — Postal shipping restrictions by item category


**Item category:** Cyclotetramethylene tetranitramine (dry or unphlegmatized) (HMX)

**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.

> Cyclotetramethylene tetranitramine (dry or unphlegmatized) (HMX) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Cyclotetramethylene tetranitramine (dry or unphlegmatized) (HMX) — Postal shipping restrictions by item category