**Item category:** Jet, perforating guns, charged oil well, with detonator

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1D, NA0124, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Jet, perforating guns, charged oil well, with detonator 1.1D NA0124 II Prohibited Prohibited

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

Jet, perforating guns, charged oil well, with detonator — Postal shipping restrictions by item category


**Item category:** Jet, perforating guns, charged oil well, without detonator

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1D, UN0124, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Jet, perforating guns, charged oil well, without detonator 1.1D UN0124 II Prohibited Prohibited

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

Jet, perforating guns, charged oil well, without detonator — Postal shipping restrictions by item category


**Item category:** Kerosene

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1223, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Kerosene 3 UN1223 III Prohibited 3A

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

Kerosene — Postal shipping restrictions by item category


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

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN1224, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Ketones, liquid, n.o.s. 3 UN1224 I Prohibited Prohibited

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

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


**Item category:** knives and sharp instruments - general

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** all domestic mail

**Conditions:** Sharp instruments include all sharp-pointed or sharp-edged implements such as knives, tools, ice picks, razor blades, stilettos, or similar devices

> Sharp instruments include all sharp-pointed or sharp-edged implements, such as knives, tools, ice picks, razor blades, stilettos, or similar devices.

Source: <https://pe.usps.com/text/pub52/pub52c4_014.htm>

knives and sharp instruments - general — Postal shipping restrictions by item category


**Item category:** Krill meal

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.2, UN3497, packing group II, III; domestic mail air: Prohibited; domestic mail surface: 4A

> Krill meal 4.2 UN3497 II, III Prohibited 4A

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

Krill meal — Postal shipping restrictions by item category


**Item category:** Krypton, compressed

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN1056, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Krypton, compressed 2.2 UN1056 n/a 2B 2B

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

Krypton, compressed — Postal shipping restrictions by item category


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

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.2, UN1970, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Krypton, refrigerated liquid (cryogenic liquid) 2.2 UN1970 n/a Prohibited Prohibited

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

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


**Item category:** Laptop / phone batteries

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic US

**Conditions:** Lithium batteries packed with equipment require hazmat declaration. Must carry lithium battery mark (Class 9). $50 noncompliance fee if undeclared, effective July 12, 2026.

> Laptop / phone batteries | Lithium battery | UN3481

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

Laptop / phone batteries — Postal shipping restrictions by item category

carrier, conditions, restriction_type, scope


**Item category:** Latex paint and water-based paint (non-flammable, non-combustible)

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** all mail

**Conditions:** Unrestricted and not regulated as a hazardous material; package per DMM 601

> Latex paint and water-based paint that are non-flammable and non-combustible are unrestricted and not regulated as a hazardous material.

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

Latex paint and water-based paint (non-flammable, non-combustible) — Postal shipping restrictions by item category

carrier, conditions, item_category, scope


**Item category:** Lead acetate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN1616, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Lead acetate 6.1 UN1616 III 6A 6A

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

Lead acetate — Postal shipping restrictions by item category


**Item category:** Lead arsenates

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1617, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lead arsenates 6.1 UN1617 II Prohibited Prohibited

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

Lead arsenates — Postal shipping restrictions by item category


**Item category:** Lead arsenites

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1618, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lead arsenites 6.1 UN1618 II Prohibited Prohibited

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

Lead arsenites — Postal shipping restrictions by item category


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

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> Lead azide (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

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


**Item category:** Lead azide, wetted with not less than 20 percent water or mixture of alcohol and water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1A, UN0129, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lead azide, wetted with not less than 20 percent water or mixture of alcohol and water, by mass 1.1A UN0129 II Prohibited Prohibited

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

Lead azide, wetted with not less than 20 percent water or mixture of alcohol and water, by mass — Postal shipping restrictions by item category


**Item category:** Lead compounds, soluble, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2291, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Lead compounds, soluble, n.o.s. 6.1 UN2291 III 6A 6A

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

Lead compounds, soluble, n.o.s. — Postal shipping restrictions by item category


**Item category:** Lead cyanide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1620, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lead cyanide 6.1 UN1620 II Prohibited Prohibited

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

Lead cyanide — Postal shipping restrictions by item category


**Item category:** Lead dioxide

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1872, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Lead dioxide 5.1 UN1872 III 5A 5A

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

Lead dioxide — Postal shipping restrictions by item category


**Item category:** Lead nitrate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, UN1469, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lead nitrate 5.1 UN1469 II Prohibited Prohibited

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

Lead nitrate — Postal shipping restrictions by item category


**Item category:** Lead nitroresorcinate (dry)

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> Lead nitroresorcinate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Lead nitroresorcinate (dry) — Postal shipping restrictions by item category


**Item category:** Lead perchlorate, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, UN1470, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lead perchlorate, solid 5.1 UN1470 II Prohibited Prohibited

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

Lead perchlorate, solid — Postal shipping restrictions by item category


**Item category:** Lead perchlorate, solution

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, UN3408, packing group II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lead perchlorate, solution 5.1 UN3408 II, III Prohibited Prohibited

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

Lead perchlorate, solution — Postal shipping restrictions by item category


**Item category:** Lead phosphite, dibasic

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN2989, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lead phosphite, dibasic 4.1 UN2989 II Prohibited Prohibited

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

Lead phosphite, dibasic — Postal shipping restrictions by item category


**Item category:** Lead picrate (dry)

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> Lead picrate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Lead picrate (dry) — Postal shipping restrictions by item category


**Item category:** Lead styphnate (dry)

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> Lead styphnate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Lead styphnate (dry) — Postal shipping restrictions by item category


**Item category:** Lead styphnate, wetted or Lead trinitroresorcinate, wetted with not less than 20 percent water or mixture of alcohol and water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1A, UN0130, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lead styphnate, wetted or Lead trinitroresorcinate, wetted with not less than 20 percent water or mixture of alcohol and water, by mass 1.1A UN0130 II Prohibited Prohibited

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

Lead styphnate, wetted or Lead trinitroresorcinate, wetted with not less than 20 percent water or mixture of alcohol and water, by mass — Postal shipping restrictions by item category


**Item category:** Lead sulfate with more than 3 percent free acid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1794, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Lead sulfate with more than 3 percent free acid 8 UN1794 II 8A 8A

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

Lead sulfate with more than 3 percent free acid — Postal shipping restrictions by item category


**Item category:** Lifesaving appliances, self-inflating

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 9, UN2990, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lifesaving appliances, self-inflating 9 UN2990 n/a Prohibited Prohibited

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

Lifesaving appliances, self-inflating — Postal shipping restrictions by item category


**Item category:** Lighter fluid

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail via surface transportation only

**Conditions:** Permitted only via surface transportation if fluid qualifies as Limited Quantity surface material and is within quantity limitations and packaging requirements; Packaging Instruction 3A must be followed

> Lighter Fluid: Considered a flammable liquid and typically has a flashpoint between 20° F (-7° C) and 55° F (13° C). It is permitted only in domestic mail via surface transportation

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

Lighter fluid — Postal shipping restrictions by item category


**Item category:** Lighter refills containing flammable gas not exceeding 4 fluid ounces (7.22 cubic inches) and 65 grams of flammable gas

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN1057, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 3C

> Lighter refills containing flammable gas not exceeding 4 fluid ounces (7.22 cubic inches) and 65 grams of flammable gas 2.1 UN1057 n/a Prohibited 3C

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

Lighter refills containing flammable gas not exceeding 4 fluid ounces (7.22 cubic inches) and 65 grams of flammable gas — Postal shipping restrictions by item category


**Item category:** Lighters containing flammable gas

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN1057, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 3C

> Lighters containing flammable gas 2.1 UN1057 n/a Prohibited 3C

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

Lighters containing flammable gas — Postal shipping restrictions by item category


**Item category:** Lighters, fuse

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.4S, UN0131, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lighters, fuse 1.4S UN0131 II Prohibited Prohibited

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

Lighters, fuse — Postal shipping restrictions by item category


**Item category:** Lighters / lighter refills

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic US

**Conditions:** Classified as flammable gas. Requires hazmat declaration. $50 noncompliance fee if undeclared, effective July 12, 2026.

> Lighters / lighter refills | Flammable gas | UN1057

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

Lighters / lighter refills — Postal shipping restrictions by item category


**Item category:** Lighters, non-pressurized, containing flammable liquid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, NA1057, packing group II; domestic mail air: Prohibited; domestic mail surface: 3C

> Lighters, non-pressurized, containing flammable liquid 3 NA1057 II Prohibited 3C

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

Lighters, non-pressurized, containing flammable liquid — Postal shipping restrictions by item category


**Item category:** Lighters with ignition elements containing liquid fuel or flammable gas

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail via surface transportation only

**Conditions:** Mailable via surface transportation only with DOT certification, PCSC director written authorization, specific packaging and labeling; shipping paper not required

> Lighters with ignition elements and containing liquid fuel are classified as a Class 3 flammable liquid; those containing flammable gas are Division 2.1. Mailing is permitted only for domestic surface transportation only

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

Lighters with ignition elements containing liquid fuel or flammable gas — Postal shipping restrictions by item category


**Item category:** Liquid Mercury

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** US Mail

**Conditions:** you must find another carrier

> Liquid mercury in any amount (and devices containing a visible amount of mercury) is prohibited from the US Mail, so you must find another carrier.

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

Liquid Mercury — Postal shipping restrictions by item category


**Item category:** Liquid with flashpoint above 200 F (93 C)

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** all mail

**Conditions:** Not regulated as hazardous material; mailable subject to general packaging requirements in DMM 601 provided it has no characteristics of another hazard class

> A liquid with a flashpoint above 200° F (93° C) is not regulated as a hazardous material and may be mailed subject to the general packaging requirements in DMM 601

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

Liquid with flashpoint above 200 F (93 C) — Postal shipping restrictions by item category


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

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN3161, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Liquified gas, flammable, n.o.s. 2.1 UN3161 n/a Prohibited 2A

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

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


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

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN3163, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Liquified gas, n.o.s. 2.2 UN3163 n/a 2B 2B

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

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


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

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN3157, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Liquified gas, oxidizing, n.o.s. 2.2 UN3157 n/a 2B 2B

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

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


**Item category:** Liquified 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, UN3308, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Liquified gas, toxic, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN3308 n/a Prohibited Prohibited

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

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


**Item category:** Liquified 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, UN3309, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Liquified gas, toxic, flammable, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN3309 n/a Prohibited Prohibited

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

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


**Item category:** Liquified 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, UN3160, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Liquified gas, toxic, flammable, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN3160 n/a Prohibited Prohibited

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

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


**Item category:** Liquified 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, UN3162, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Liquified gas, toxic, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN3162 n/a Prohibited Prohibited

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

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


**Item category:** Liquified 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, UN3310, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Liquified gas, toxic, oxidizing, corrosive, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN3310 n/a Prohibited Prohibited

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

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


**Item category:** Liquified 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, UN3307, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Liquified gas, toxic, oxidizing, n.o.s. Inhalation Hazard Zone A, B, C, or D 2.3 UN3307 n/a Prohibited Prohibited

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

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


**Item category:** Liquified gases, nonflammable charged with nitrogen, carbon dioxide, or air

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN1058, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Liquified gases, nonflammable charged with nitrogen, carbon dioxide, or air 2.2 UN1058 n/a 2B 2B

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

Liquified gases, nonflammable charged with nitrogen, carbon dioxide, or air — Postal shipping restrictions by item category


**Item category:** Lithium aluminum hydride, ethereal

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN1411, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lithium aluminum hydride, ethereal 4.3 UN1411 I Prohibited Prohibited

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

Lithium aluminum hydride, ethereal — Postal shipping restrictions by item category


**Item category:** Lithium Batteries

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** ground only

**Conditions:** These devices must be marked on the outer packaging with the text, " Restricted Electronic Device " and " Surface Transportation Only ."

> These devices must be marked on the outer packaging with the text, " Restricted Electronic Device " and " Surface Transportation Only ."

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

Lithium Batteries — Postal shipping restrictions by item category


**Item category:** Lithium borohydride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN1413, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Lithium borohydride 4.3 UN1413 I Prohibited Prohibited

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

Lithium borohydride — Postal shipping restrictions by item category


**Item category:** Lithium ferrosilicon

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.3, UN2830, packing group II; domestic mail air: Prohibited; domestic mail surface: 4A

> Lithium ferrosilicon 4.3 UN2830 II Prohibited 4A

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

Lithium ferrosilicon — Postal shipping restrictions by item category


**Item category:** Lithium hydride, fused solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.3, UN2805, packing group II; domestic mail air: Prohibited; domestic mail surface: 4A

> Lithium hydride, fused solid 4.3 UN2805 II Prohibited 4A

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

Lithium hydride, fused solid — Postal shipping restrictions by item category


**Item category:** Lithium hydride

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.3, UN1414, packing group I; domestic mail air: Prohibited; domestic mail surface: 4A

> Lithium hydride 4.3 UN1414 I Prohibited 4A

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

Lithium hydride — Postal shipping restrictions by item category


**Item category:** Lithium hydroxide, monohydrate or Lithium hydroxide, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2680, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Lithium hydroxide, monohydrate or Lithium hydroxide, solid 8 UN2680 II 8A 8A

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

Lithium hydroxide, monohydrate or Lithium hydroxide, solid — Postal shipping restrictions by item category


**Item category:** Lithium hydroxide, solution

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2679, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Lithium hydroxide, solution 8 UN2679 II, III 8A 8A

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

Lithium hydroxide, solution — Postal shipping restrictions by item category


**Item category:** Lithium hypochlorite, dry or Lithium hypochlorite mixture

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1471, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Lithium hypochlorite, dry or Lithium hypochlorite mixture 5.1 UN1471 II 5A 5A

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

Lithium hypochlorite, dry or Lithium hypochlorite mixture — Postal shipping restrictions by item category


**Item category:** Lithium-ion batteries (including lithium polymer batteries) contained in equipment

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 9, UN3481, packing group not stated; domestic mail air: 9D; domestic mail surface: 9D

> Lithium-ion batteries (including lithium polymer batteries) contained in equipment 9 UN3481 N/A 9D 9D

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

Lithium-ion batteries (including lithium polymer batteries) contained in equipment — Postal shipping restrictions by item category


**Item category:** Lithium-ion batteries (including lithium polymer batteries) packed with equipment

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 9, UN3481, packing group not stated; domestic mail air: 9D; domestic mail surface: 9D

> Lithium-ion batteries (including lithium polymer batteries) packed with equipment 9 UN3481 N/A 9D 9D

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

Lithium-ion batteries (including lithium polymer batteries) packed with equipment — Postal shipping restrictions by item category


**Item category:** Lithium-ion batteries (including lithium polymer batteries)

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 9, UN3480, packing group not stated; domestic mail air: Prohibited; domestic mail surface: 9D

> Lithium-ion batteries (including lithium polymer batteries) 9 UN3480 N/A Prohibited 9D

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

Lithium-ion batteries (including lithium polymer batteries) — Postal shipping restrictions by item category


**Item category:** Lithium-ion (rechargeable) batteries without equipment (individual batteries)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail via air transportation (except intra-Alaska)

**Conditions:** Individual lithium-ion batteries without equipment are prohibited from domestic air transportation except intra-Alaska; mailable via surface only up to 5 lbs with proper markings

> Lithium-ion or Lithium Polymer Batteries 5, 6

Source: <https://pe.usps.com/text/pub52/pub52c3_028.htm>

Lithium-ion (rechargeable) batteries without equipment (individual batteries) — Postal shipping restrictions by item category

carrier, conditions, item_category, restriction_type, scope


**Item category:** Lithium metal batteries (including lithium alloy batteries) contained in equipment

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 9, UN3091, packing group not stated; domestic mail air: 9D; domestic mail surface: 9D

> Lithium metal batteries (including lithium alloy batteries) contained in equipment 9 UN3091 N/A 9D 9D

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

Lithium metal batteries (including lithium alloy batteries) contained in equipment — Postal shipping restrictions by item category


**Item category:** Lithium metal batteries (including lithium alloy batteries) packed with equipment

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 9, UN3091, packing group not stated; domestic mail air: 9D; domestic mail surface: 9D

> Lithium metal batteries (including lithium alloy batteries) packed with equipment 9 UN3091 N/A 9D 9D

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

Lithium metal batteries (including lithium alloy batteries) packed with equipment — Postal shipping restrictions by item category


**Item category:** Lithium metal batteries (including lithium alloy batteries)

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 9, UN3090, packing group not stated; domestic mail air: Prohibited; domestic mail surface: 9D

> Lithium metal batteries (including lithium alloy batteries) 9 UN3090 N/A Prohibited 9D

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

Lithium metal batteries (including lithium alloy batteries) — Postal shipping restrictions by item category


**Item category:** Lithium metal (non-rechargeable) batteries without equipment (individual batteries)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic mail via air transportation

**Conditions:** Individual lithium metal batteries without equipment are prohibited from domestic air transportation; mailable via surface only in sealed packaging up to 5 lbs with proper markings

> Without the equipment they operate (individual batteries in originally sealed packaging)

Source: <https://pe.usps.com/text/pub52/pub52c3_028.htm>

Lithium metal (non-rechargeable) batteries without equipment (individual batteries) — Postal shipping restrictions by item category


**Item category:** Lithium peroxide

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1472, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Lithium peroxide 5.1 UN1472 II 5A 5A

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

Lithium peroxide — Postal shipping restrictions by item category


**Item category:** Lithium silicon

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.3, UN1417, packing group II; domestic mail air: Prohibited; domestic mail surface: 5A

> Lithium silicon 4.3 UN1417 II Prohibited 5A

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

Lithium silicon — Postal shipping restrictions by item category


**Item category:** Lithium

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.3, UN1415, packing group I; domestic mail air: Prohibited; domestic mail surface: 4A

> Lithium 4.3 UN1415 I Prohibited 4A

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

Lithium — Postal shipping restrictions by item category


**Item category:** Live Animals

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic

**Conditions:** Shipments of live animals, including poultry, reptiles, and bees, have very specific packaging requirements.

> Shipments of live animals, including poultry, reptiles, and bees, have very specific packaging requirements.

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

Live Animals — Postal shipping restrictions by item category


**Item category:** live day-old poultry - mailable types

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** domestic mail

**Conditions:** Mailable types include chickens, ducks, emus, geese, guinea birds, partridges, pheasants (April through August only), quail, turkeys; all other types of live day-old poultry are nonmailable; must be no more than 24 hours old

> The following types of live, day-old poultry are acceptable for mailing when properly packaged:

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

live day-old poultry - mailable types — Postal shipping restrictions by item category


**Item category:** live day-old poultry vaccinated with Newcastle disease (live virus)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all domestic mail

**Conditions:** Day-old poultry vaccinated with Newcastle disease (live virus) is nonmailable

> Day-old poultry vaccinated with Newcastle disease (live virus) also is nonmailable.

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

live day-old poultry vaccinated with Newcastle disease (live virus) — Postal shipping restrictions by item category


**Item category:** live scorpions

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Scorpions are mailable only when sent for the purposes of medical research or the manufacturing of antivenin; must be sent by surface transportation within continental United States; must be properly packaged in double container system

> scorpions are mailable only when sent for the purposes of medical research or the manufacturing of antivenin. Scorpions are nonmailable under any other circumstances.

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

live scorpions — Postal shipping restrictions by item category


**Item category:** London purple

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN1621, packing group II; domestic mail air: 6A; domestic mail surface: 6A

> London purple 6.1 UN1621 II 6A 6A

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

London purple — Postal shipping restrictions by item category


**Item category:** Low-risk radioactive material (UN2910) — limited quantity excepted package

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail via surface transportation

**Conditions:** Mailable if activity does not exceed limits in Exhibit 347.22; classified as limited quantity excepted package per 49 CFR 172.101; must follow Packaging Instruction 7A

> UN2910: Low-risk radioactive material classified as "limited quantity" and "excepted package" under 49 CFR § 172.101.

Source: <https://pe.usps.com/text/pub52/pub52c3_026.htm>

Low-risk radioactive material (UN2910) — limited quantity excepted package — Postal shipping restrictions by item category


**Item category:** m-Nitrobenzene diazonium perchlorate

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> m-Nitrobenzene diazonium perchlorate Forbidden Prohibited Prohibited Prohibited Prohibited

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

m-Nitrobenzene diazonium perchlorate — Postal shipping restrictions by item category


**Item category:** m-Nitrophenyldinitro methane

**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.

> m-Nitrophenyldinitro methane Forbidden Prohibited Prohibited Prohibited Prohibited

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

m-Nitrophenyldinitro methane — Postal shipping restrictions by item category


**Item category:** m-Phenylene diaminediperchlorate (dry)

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> m-Phenylene diaminediperchlorate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

m-Phenylene diaminediperchlorate (dry) — Postal shipping restrictions by item category


**Item category:** Magnesium aluminum phosphide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN1419, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Magnesium aluminum phosphide 4.3 UN1419 I Prohibited Prohibited

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

Magnesium aluminum phosphide — Postal shipping restrictions by item category


**Item category:** Magnesium arsenate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1622, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Magnesium arsenate 6.1 UN1622 II Prohibited Prohibited

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

Magnesium arsenate — Postal shipping restrictions by item category


**Item category:** Magnesium bromate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1473, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Magnesium bromate 5.1 UN1473 II 5A 5A

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

Magnesium bromate — Postal shipping restrictions by item category


**Item category:** Magnesium chlorate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN2723, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Magnesium chlorate 5.1 UN2723 II 5A 5A

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

Magnesium chlorate — Postal shipping restrictions by item category


**Item category:** Magnesium diamide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN2004, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Magnesium diamide 4.2 UN2004 II Prohibited Prohibited

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

Magnesium diamide — Postal shipping restrictions by item category


**Item category:** Magnesium dross, wet or 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.

> Magnesium dross, wet or hot Forbidden Prohibited Prohibited Prohibited Prohibited

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

Magnesium dross, wet or hot — Postal shipping restrictions by item category


**Item category:** Magnesium fluorosilicate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2853, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Magnesium fluorosilicate 6.1 UN2853 III 6A 6A

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

Magnesium fluorosilicate — Postal shipping restrictions by item category


**Item category:** Magnesium granules, coated particle size not less than 149 microns

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN2950, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Magnesium granules, coated particle size not less than 149 microns 4.3 UN2950 III Prohibited Prohibited

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

Magnesium granules, coated particle size not less than 149 microns — Postal shipping restrictions by item category


**Item category:** Magnesium hydride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN2010, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Magnesium hydride 4.3 UN2010 I Prohibited Prohibited

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

Magnesium hydride — Postal shipping restrictions by item category


**Item category:** Magnesium nitrate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1474, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Magnesium nitrate 5.1 UN1474 III 5A 5A

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

Magnesium nitrate — Postal shipping restrictions by item category


**Item category:** Magnesium or Magnesium alloys with more than 50 percent magnesium in pellets, turnings, or ribbons

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.1, UN1869, packing group III; domestic mail air: Prohibited; domestic mail surface: 4A

> Magnesium or Magnesium alloys with more than 50 percent magnesium in pellets, turnings, or ribbons 4.1 UN1869 III Prohibited 4A

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

Magnesium or Magnesium alloys with more than 50 percent magnesium in pellets, turnings, or ribbons — Postal shipping restrictions by item category


**Item category:** Magnesium perchlorate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1475, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Magnesium perchlorate 5.1 UN1475 II 5A 5A

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

Magnesium perchlorate — Postal shipping restrictions by item category


**Item category:** Magnesium peroxide

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1476, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Magnesium peroxide 5.1 UN1476 II 5A 5A

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

Magnesium peroxide — Postal shipping restrictions by item category


**Item category:** Magnesium phosphide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN2011, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Magnesium phosphide 4.3 UN2011 I Prohibited Prohibited

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

Magnesium phosphide — Postal shipping restrictions by item category


**Item category:** Magnesium, powder or Magnesium alloys, powder

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN1418, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Magnesium, powder or Magnesium alloys, powder 4.3 UN1418 I Prohibited Prohibited

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

Magnesium, powder or Magnesium alloys, powder — Postal shipping restrictions by item category


**Item category:** Magnesium silicide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN2624, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Magnesium silicide 4.3 UN2624 II Prohibited Prohibited

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

Magnesium silicide — Postal shipping restrictions by item category


**Item category:** Magnetized materials — domestic surface transportation

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** domestic mail via surface transportation

**Conditions:** Magnetized materials are not regulated as hazardous when transported via surface transportation

> Domestic Mail via Surface Transportation: Magnetized materials are not regulated as hazardous when transported via surface transportation.

Source: <https://pe.usps.com/text/pub52/pub52c3_028.htm>

Magnetized materials — domestic surface transportation — Postal shipping restrictions by item category


**Item category:** Magnetized materials with field strength exceeding 0.00525 gauss at 15 feet

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all domestic and international air transportation

**Conditions:** Prohibited from air transportation under any circumstances

> Materials with a field strength over 0.00525 gauss at 15 feet are nonmailable in domestic and international air transportation under any circumstances.

Source: <https://pe.usps.com/text/pub52/pub52c3_028.htm>

Magnetized materials with field strength exceeding 0.00525 gauss at 15 feet — Postal shipping restrictions by item category


**Item category:** Maleic anhydride, molten

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2215, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Maleic anhydride, molten 8 UN2215 III Prohibited Prohibited

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

Maleic anhydride, molten — Postal shipping restrictions by item category


**Item category:** Maleic anhydride

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2215, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Maleic anhydride 8 UN2215 III 8A 8A

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

Maleic anhydride — Postal shipping restrictions by item category


**Item category:** Malononitrile

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2647, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Malononitrile 6.1 UN2647 II Prohibited Prohibited

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

Malononitrile — Postal shipping restrictions by item category


**Item category:** Maneb stabilized or Maneb preparations, stabilized against self- heating

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN2968, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Maneb stabilized or Maneb preparations, stabilized against self- heating 4.3 UN2968 III Prohibited Prohibited

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

Maneb stabilized or Maneb preparations, stabilized against self- heating — Postal shipping restrictions by item category


**Item category:** Manganese nitrate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN2724, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Manganese nitrate 5.1 UN2724 III 5A 5A

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

Manganese nitrate — Postal shipping restrictions by item category


**Item category:** Manganese resinate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.1, UN1330, packing group III; domestic mail air: Prohibited; domestic mail surface: 4A

> Manganese resinate 4.1 UN1330 III Prohibited 4A

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

Manganese resinate — Postal shipping restrictions by item category


**Item category:** Mannitan tetranitrate

**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.

> Mannitan tetranitrate Forbidden Prohibited Prohibited Prohibited Prohibited

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

Mannitan tetranitrate — Postal shipping restrictions by item category


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

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> Mannitol hexanitrate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

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


**Item category:** Mannitol hexanitrate, wetted or Nitromannite, wetted with not less than 40 percent water, or mixture of alcohol and water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1D, UN0133, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mannitol hexanitrate, wetted or Nitromannite, wetted with not less than 40 percent water, or mixture of alcohol and water, by mass 1.1D UN0133 II Prohibited Prohibited

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

Mannitol hexanitrate, wetted or Nitromannite, wetted with not less than 40 percent water, or mixture of alcohol and water, by mass — Postal shipping restrictions by item category


**Item category:** Marijuana

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic

**Conditions:** Medical or otherwise prohibited; hemp/CBD is allowed but restricted

> Marijuana (medical or otherwise); hemp/CBD is allowed, but restricted

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

Marijuana — Postal shipping restrictions by item category


**Item category:** Matches, fusee

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN2254, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Matches, fusee 4.1 UN2254 III Prohibited Prohibited

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

Matches, fusee — Postal shipping restrictions by item category


**Item category:** Matches, safety (book, card, or strike on box)

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.1, UN1944, packing group III; domestic mail air: Prohibited; domestic mail surface: 4B

> Matches, safety (book, card, or strike on box) 4.1 UN1944 III Prohibited 4B

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

Matches, safety (book, card, or strike on box) — Postal shipping restrictions by item category


**Item category:** Matches, strike anywhere

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN1331, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Matches, strike anywhere 4.1 UN1331 III Prohibited Prohibited

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

Matches, strike anywhere — Postal shipping restrictions by item category


**Item category:** Matches, wax, Vesta

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN1945, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Matches, wax, Vesta 4.1 UN1945 III Prohibited Prohibited

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

Matches, wax, Vesta — Postal shipping restrictions by item category


**Item category:** Medicine, liquid, flammable, toxic, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN3248, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Medicine, liquid, flammable, toxic, n.o.s. 3 UN3248 III Prohibited 3A

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

Medicine, liquid, flammable, toxic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Medicine, liquid, toxic, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN1851, packing group II, III; domestic mail air: 6A; domestic mail surface: 6A

> Medicine, liquid, toxic, n.o.s. 6.1 UN1851 II, III 6A 6A

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

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


**Item category:** Medicine, solid, toxic, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN3249, packing group II, III; domestic mail air: 6A; domestic mail surface: 6A

> Medicine, solid, toxic, n.o.s. 6.1 UN3249 II, III 6A 6A

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

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


**Item category:** Medicines & Prescription Drugs

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic

**Conditions:** Prescription medications may only be mailed by Drug Enforcement Administration (DEA) registered distributors.

> Prescription medications may only be mailed by Drug Enforcement Administration (DEA) registered distributors.

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

Medicines & Prescription Drugs — Postal shipping restrictions by item category


**Item category:** Mercaptans, liquid, flammable, n.o.s. or Mercaptan mixture, liquid, flammable, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN3336, packing group I, II, III; domestic mail air: Prohibited; domestic mail surface: 3A

> Mercaptans, liquid, flammable, n.o.s. or Mercaptan mixture, liquid, flammable, n.o.s. 3 UN3336 I, II, III Prohibited 3A

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

Mercaptans, liquid, flammable, n.o.s. or Mercaptan mixture, liquid, flammable, n.o.s. — Postal shipping restrictions by item category


**Item category:** Mercaptans, liquid, flammable, toxic, n.o.s. or Mercaptan mixtures, liquid, flammable, toxic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN1228, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercaptans, liquid, flammable, toxic, n.o.s. or Mercaptan mixtures, liquid, flammable, toxic, n.o.s. 3 UN1228 II Prohibited Prohibited

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

Mercaptans, liquid, flammable, toxic, n.o.s. or Mercaptan mixtures, liquid, flammable, toxic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Mercaptans, liquid, toxic, flammable, n.o.s. or Mercaptan mixtures, liquid, toxic, flammable, n.o.s., flashpoint not less than 23° C

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3071, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercaptans, liquid, toxic, flammable, n.o.s. or Mercaptan mixtures, liquid, toxic, flammable, n.o.s., flashpoint not less than 23° C 6.1 UN3071 II Prohibited Prohibited

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

Mercaptans, liquid, toxic, flammable, n.o.s. or Mercaptan mixtures, liquid, toxic, flammable, n.o.s., flashpoint not less than 23° C — Postal shipping restrictions by item category


**Item category:** Mercuric arsenate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1623, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercuric arsenate 6.1 UN1623 II Prohibited Prohibited

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

Mercuric arsenate — Postal shipping restrictions by item category


**Item category:** Mercuric chloride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1624, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercuric chloride 6.1 UN1624 II Prohibited Prohibited

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

Mercuric chloride — Postal shipping restrictions by item category


**Item category:** Mercuric potassium cyanide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1626, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercuric potassium cyanide 6.1 UN1626 I Prohibited Prohibited

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

Mercuric potassium cyanide — Postal shipping restrictions by item category


**Item category:** Mercurous 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.

> Mercurous azide Forbidden Prohibited Prohibited Prohibited Prohibited

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

Mercurous azide — Postal shipping restrictions by item category


**Item category:** Mercury

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2809, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury 8 UN2809 III Prohibited Prohibited

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

Mercury — Postal shipping restrictions by item category


**Item category:** Mercury acetate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1629, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury acetate 6.1 UN1629 II Prohibited Prohibited

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

Mercury acetate — Postal shipping restrictions by item category


**Item category:** Mercury 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.

> Mercury acetylide Forbidden Prohibited Prohibited Prohibited Prohibited

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

Mercury acetylide — Postal shipping restrictions by item category


**Item category:** Mercury ammonium chloride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1630, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury ammonium chloride 6.1 UN1630 II Prohibited Prohibited

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

Mercury ammonium chloride — Postal shipping restrictions by item category


**Item category:** Mercury and mercury-containing devices (UN2809)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Nonmailable; includes metallic mercury and thermometers, barometers, sphygmomanometers containing metallic mercury

> Mercury and Mercury-Containing Devices (UN2809): Includes metallic mercury and items such as thermometers, barometers, and sphygmomanometers (i.e., blood pressure meters) that contain metallic mercury.

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

Mercury and mercury-containing devices (UN2809) — Postal shipping restrictions by item category


**Item category:** Mercury 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, UN2778, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury based pesticides, liquid, flammable, toxic, flashpoint less than 23° C 3 UN2778 I, II Prohibited Prohibited

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

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


**Item category:** Mercury 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, UN3011, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury based pesticides, liquid, toxic, flammable, flashpoint not less than 23° C 6.1 UN3011 I, II Prohibited Prohibited

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

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


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

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3012, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury based pesticides, liquid, toxic 6.1 UN3012 I, II Prohibited Prohibited

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

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


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

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2777, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury based pesticides, solid, toxic 6.1 UN2777 I, II Prohibited Prohibited

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

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


**Item category:** Mercury benzoate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1631, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury benzoate 6.1 UN1631 II Prohibited Prohibited

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

Mercury benzoate — Postal shipping restrictions by item category


**Item category:** Mercury bromides

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1634, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury bromides 6.1 UN1634 II Prohibited Prohibited

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

Mercury bromides — Postal shipping restrictions by item category


**Item category:** Mercury compounds, liquid, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2024, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury compounds, liquid, n.o.s. 6.1 UN2024 I, II Prohibited Prohibited

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

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


**Item category:** Mercury compounds, solid, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2025, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury compounds, solid, n.o.s. 6.1 UN2025 I, II Prohibited Prohibited

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

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


**Item category:** Mercury contained in manufactured articles

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN3506, packing group III; domestic mail air: 8C; domestic mail surface: 8C

> Mercury contained in manufactured articles 8 UN3506 III 8C 8C

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

Mercury contained in manufactured articles — Postal shipping restrictions by item category


**Item category:** Mercury cyanide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1636, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury cyanide 6.1 UN1636 II Prohibited Prohibited

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

Mercury cyanide — Postal shipping restrictions by item category


**Item category:** Mercury fulminate, wetted with not less than 20 percent water, or mixture of alcohol and water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1A, UN0135, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury fulminate, wetted with not less than 20 percent water, or mixture of alcohol and water, by mass 1.1A UN0135 II Prohibited Prohibited

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

Mercury fulminate, wetted with not less than 20 percent water, or mixture of alcohol and water, by mass — Postal shipping restrictions by item category


**Item category:** Mercury gluconate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1637, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury gluconate 6.1 UN1637 II Prohibited Prohibited

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

Mercury gluconate — Postal shipping restrictions by item category


**Item category:** Mercury iodide aquabasic ammonobasic (Iodide of Millon’s base)

**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.

> Mercury iodide aquabasic ammonobasic (Iodide of Millon’s base) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Mercury iodide aquabasic ammonobasic (Iodide of Millon’s base) — Postal shipping restrictions by item category


**Item category:** Mercury iodide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1638, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury iodide 6.1 UN1638 II Prohibited Prohibited

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

Mercury iodide — Postal shipping restrictions by item category


**Item category:** Mercury nitride

**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.

> Mercury nitride Forbidden Prohibited Prohibited Prohibited Prohibited

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

Mercury nitride — Postal shipping restrictions by item category


**Item category:** Mercury nucleate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1639, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury nucleate 6.1 UN1639 II Prohibited Prohibited

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

Mercury nucleate — Postal shipping restrictions by item category


**Item category:** Mercury oleate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1640, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury oleate 6.1 UN1640 II Prohibited Prohibited

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

Mercury oleate — Postal shipping restrictions by item category


**Item category:** Mercury oxide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1641, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury oxide 6.1 UN1641 II Prohibited Prohibited

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

Mercury oxide — Postal shipping restrictions by item category


**Item category:** Mercury oxycyanide, desensitized

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1642, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury oxycyanide, desensitized 6.1 UN1642 II Prohibited Prohibited

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

Mercury oxycyanide, desensitized — Postal shipping restrictions by item category


**Item category:** Mercury oxycyanide

**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.

> Mercury oxycyanide Forbidden Prohibited Prohibited Prohibited Prohibited

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

Mercury oxycyanide — Postal shipping restrictions by item category


**Item category:** Mercury potassium iodide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1643, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury potassium iodide 6.1 UN1643 II Prohibited Prohibited

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

Mercury potassium iodide — Postal shipping restrictions by item category


**Item category:** Mercury salicylate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1644, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury salicylate 6.1 UN1644 II Prohibited Prohibited

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

Mercury salicylate — Postal shipping restrictions by item category


**Item category:** Mercury sulfates

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1645, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury sulfates 6.1 UN1645 II Prohibited Prohibited

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

Mercury sulfates — Postal shipping restrictions by item category


**Item category:** Mercury thiocyanate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1646, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mercury thiocyanate 6.1 UN1646 II Prohibited Prohibited

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

Mercury thiocyanate — Postal shipping restrictions by item category


**Item category:** Mercury Vapor Devices

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic

**Conditions:** These items are restricted, but mailable

> Some consumer devices, like compact fluorescent light bulbs, contain tiny amounts of mercury vapor. These items are restricted, but mailable.

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

Mercury Vapor Devices — Postal shipping restrictions by item category


**Item category:** Mercury

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** US Mail

**Conditions:** Liquid mercury in any amount (and devices containing a visible amount of mercury) is prohibited from the US Mail, so you must find another carrier.

> Liquid mercury in any amount (and devices containing a visible amount of mercury) is prohibited from the US Mail, so you must find another carrier.

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

Mercury — Postal shipping restrictions by item category


**Item category:** Mesityl oxide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN1229, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Mesityl oxide 3 UN1229 III Prohibited Prohibited

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

Mesityl oxide — Postal shipping restrictions by item category


**Item category:** Metal carbonyls, liquid, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3281, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Metal carbonyls, liquid, n.o.s. 6.1 UN3281 I, II Prohibited Prohibited

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

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


**Item category:** Metal carbonyls, solid, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3466, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Metal carbonyls, solid, n.o.s. 6.1 UN3466 I, II Prohibited Prohibited

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

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


**Item category:** Metal catalyst, dry

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN2881, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Metal catalyst, dry 4.2 UN2881 I, II Prohibited Prohibited

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

Metal catalyst, dry — Postal shipping restrictions by item category


**Item category:** Metal catalyst, wetted with a visible excess of liquid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN1378, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Metal catalyst, wetted with a visible excess of liquid 4.2 UN1378 II Prohibited Prohibited

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

Metal catalyst, wetted with a visible excess of liquid — Postal shipping restrictions by item category


**Item category:** Metal hydrides, flammable, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.1, UN3182, packing group II, III; domestic mail air: Prohibited; domestic mail surface: 3A

> Metal hydrides, flammable, n.o.s. 4.1 UN3182 II, III Prohibited 3A

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

Metal hydrides, flammable, n.o.s. — Postal shipping restrictions by item category


**Item category:** Metal hydrides, water reactive, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN1409, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Metal hydrides, water reactive, n.o.s. 4.3 UN1409 I Prohibited Prohibited

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

Metal hydrides, water reactive, n.o.s. — Postal shipping restrictions by item category


**Item category:** Metal mercury (mercury thermometers, barometers, blood pressure monitors)

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** USPS never allows metal mercury to be mailed

> Note the USPS never allows explosives or metal mercury (such as mercury thermometers, mercury barometers, mercury blood pressure monitors) to be mailed.

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

Metal mercury (mercury thermometers, barometers, blood pressure monitors) — Postal shipping restrictions by item category


**Item category:** Metal powder, self-heating, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN3189, packing group II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Metal powder, self-heating, n.o.s. 4.2 UN3189 II, III Prohibited Prohibited

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

Metal powder, self-heating, n.o.s. — Postal shipping restrictions by item category


**Item category:** Metal powders, flammable, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.1, UN3089, packing group II, III; domestic mail air: Prohibited; domestic mail surface: 4A

> Metal powders, flammable, n.o.s. 4.1 UN3089 II, III Prohibited 4A

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

Metal powders, flammable, n.o.s. — Postal shipping restrictions by item category


**Item category:** Metal salts of methyl nitramine (dry)

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> Metal salts of methyl nitramine (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Metal salts of methyl nitramine (dry) — Postal shipping restrictions by item category


**Item category:** Metal salts of organic compounds, flammable, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.1, UN3181, packing group II, III; domestic mail air: Prohibited; domestic mail surface: 4A

> Metal salts of organic compounds, flammable, n.o.s. 4.1 UN3181 II, III Prohibited 4A

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

Metal salts of organic compounds, flammable, n.o.s. — Postal shipping restrictions by item category


**Item category:** Metaldehyde

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.1, UN1332, packing group III; domestic mail air: Prohibited; domestic mail surface: 4A

> Metaldehyde 4.1 UN1332 III Prohibited 4A

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

Metaldehyde — Postal shipping restrictions by item category


**Item category:** Metallic substance, water reactive, self-heating, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN3209, packing group I, II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Metallic substance, water reactive, self-heating, n.o.s. 4.3 UN3209 I, II, III Prohibited Prohibited

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

Metallic substance, water reactive, self-heating, n.o.s. — Postal shipping restrictions by item category


**Item category:** Metallic substances, water reactive, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN3208, packing group I, II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Metallic substances, water reactive, n.o.s. 4.3 UN3208 I, II, III Prohibited Prohibited

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

Metallic substances, water reactive, n.o.s. — Postal shipping restrictions by item category


**Item category:** Methacrylaldehyde, inhibited

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN2396, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methacrylaldehyde, inhibited 3 UN2396 II Prohibited Prohibited

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

Methacrylaldehyde, inhibited — Postal shipping restrictions by item category


**Item category:** Methacrylic acid, inhibited

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2531, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Methacrylic acid, inhibited 8 UN2531 III 8A 8A

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

Methacrylic acid, inhibited — Postal shipping restrictions by item category


**Item category:** Methacrylonitrile, inhibited

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN3079, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methacrylonitrile, inhibited 3 UN3079 I Prohibited Prohibited

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

Methacrylonitrile, inhibited — Postal shipping restrictions by item category


**Item category:** Methallyl alcohol

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2614, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Methallyl alcohol 3 UN2614 III Prohibited 3A

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

Methallyl alcohol — Postal shipping restrictions by item category


**Item category:** Methane, refrigerated liquid (cryogenic liquid) or Natural gas, refrigerated liquid (cryogenic liquid), with high methane content

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN1972, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Methane, refrigerated liquid (cryogenic liquid) or Natural gas, refrigerated liquid (cryogenic liquid), with high methane content 2.1 UN1972 n/a Prohibited 2A

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

Methane, refrigerated liquid (cryogenic liquid) or Natural gas, refrigerated liquid (cryogenic liquid), with high methane content — Postal shipping restrictions by item category


**Item category:** Methanesulfonyl chloride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3246, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methanesulfonyl chloride 6.1 UN3246 I Prohibited Prohibited

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

Methanesulfonyl chloride — Postal shipping restrictions by item category


**Item category:** Methanol

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1230, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Methanol 3 UN1230 II Prohibited 3A

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

Methanol — Postal shipping restrictions by item category


**Item category:** Methazoic acid

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> Methazoic acid Forbidden Prohibited Prohibited Prohibited Prohibited

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

Methazoic acid — Postal shipping restrictions by item category


**Item category:** Methoxymethyl isocyanate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2605, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methoxymethyl isocyanate 6.1 UN2605 I Prohibited Prohibited

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

Methoxymethyl isocyanate — Postal shipping restrictions by item category


**Item category:** Methyl-2-chloropropionate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2933, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Methyl-2-chloropropionate 3 UN2933 III Prohibited 3A

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

Methyl-2-chloropropionate — Postal shipping restrictions by item category


**Item category:** Methyl acetate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1231, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Methyl acetate 3 UN1231 II Prohibited 3A

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

Methyl acetate — Postal shipping restrictions by item category


**Item category:** Methyl acetylene and propadiene mixtures, stabilized

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN1060, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Methyl acetylene and propadiene mixtures, stabilized 2.1 UN1060 n/a Prohibited 2A

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

Methyl acetylene and propadiene mixtures, stabilized — Postal shipping restrictions by item category


**Item category:** Methyl acrylate, stabilized

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1919, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Methyl acrylate, stabilized 3 UN1919 II Prohibited 3A

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

Methyl acrylate, stabilized — Postal shipping restrictions by item category


**Item category:** Methyl allyl chloride

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2554, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Methyl allyl chloride 3 UN2554 II Prohibited 3A

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

Methyl allyl chloride — Postal shipping restrictions by item category


**Item category:** Methyl bromide and ethylene dibromide mixtures, liquid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1647, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methyl bromide and ethylene dibromide mixtures, liquid 6.1 UN1647 I Prohibited Prohibited

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

Methyl bromide and ethylene dibromide mixtures, liquid — Postal shipping restrictions by item category


**Item category:** Methyl bromide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1062, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methyl bromide 2.3 UN1062 n/a Prohibited Prohibited

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

Methyl bromide — Postal shipping restrictions by item category


**Item category:** Methyl bromoacetate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2643, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methyl bromoacetate 6.1 UN2643 II Prohibited Prohibited

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

Methyl bromoacetate — Postal shipping restrictions by item category


**Item category:** Methyl butyrate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1237, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Methyl butyrate 3 UN1237 II Prohibited 3A

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

Methyl butyrate — Postal shipping restrictions by item category


**Item category:** Methyl chloride and methylene chloride mixtures

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN1912, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Methyl chloride and methylene chloride mixtures 2.1 UN1912 n/a Prohibited 2A

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

Methyl chloride and methylene chloride mixtures — Postal shipping restrictions by item category


**Item category:** Methyl chloride, or Refrigerant gas R 40

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN1063, packing group not stated; domestic mail air: Prohibited; domestic mail surface: 2A

> Methyl chloride, or Refrigerant gas R 40 2.1 UN1063 Prohibited 2A

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

Methyl chloride, or Refrigerant gas R 40 — Postal shipping restrictions by item category


**Item category:** Methyl chloroacetate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2295, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methyl chloroacetate 6.1 UN2295 I Prohibited Prohibited

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

Methyl chloroacetate — Postal shipping restrictions by item category


**Item category:** Methyl chloroformate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1238, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methyl chloroformate 6.1 UN1238 I Prohibited Prohibited

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

Methyl chloroformate — Postal shipping restrictions by item category


**Item category:** Methyl chloromethyl ether

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1239, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methyl chloromethyl ether 6.1 UN1239 I Prohibited Prohibited

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

Methyl chloromethyl ether — Postal shipping restrictions by item category


**Item category:** Methyl dichloroacetate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2299, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Methyl dichloroacetate 6.1 UN2299 III 6A 6A

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

Methyl dichloroacetate — Postal shipping restrictions by item category


**Item category:** Methyl ethyl ketone peroxide, in solution with more than 9 percent by mass active oxygen

**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.

> Methyl ethyl ketone peroxide, in solution with more than 9 percent by mass active oxygen Forbidden Prohibited Prohibited Prohibited Prohibited

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

Methyl ethyl ketone peroxide, in solution with more than 9 percent by mass active oxygen — Postal shipping restrictions by item category


**Item category:** Methyl fluoride, or Refrigerant gas R 41

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN2454, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Methyl fluoride, or Refrigerant gas R 41 2.1 UN2454 n/a Prohibited 2A

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

Methyl fluoride, or Refrigerant gas R 41 — Postal shipping restrictions by item category


**Item category:** Methyl formate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1243, packing group I; domestic mail air: Prohibited; domestic mail surface: 3A

> Methyl formate 3 UN1243 I Prohibited 3A

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

Methyl formate — Postal shipping restrictions by item category


**Item category:** Methyl iodide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2644, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Methyl iodide 6.1 UN2644 I Prohibited Prohibited

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

Methyl iodide — Postal shipping restrictions by item category


**Item category:** Methyl isobutyl carbinol

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2053, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Methyl isobutyl carbinol 3 UN2053 III Prohibited 3A

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

Methyl isobutyl carbinol — Postal shipping restrictions by item category


**Item category:** Methyl isobutyl ketone peroxide, in solution with more than 9 percent by mass active oxygen

**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.

> Methyl isobutyl ketone peroxide, in solution with more than 9 percent by mass active oxygen Forbidden Prohibited Prohibited Prohibited Prohibited

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

Methyl isobutyl ketone peroxide, in solution with more than 9 percent by mass active oxygen — Postal shipping restrictions by item category