**Item category:** Self-heating solid, inorganic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN3190, packing group II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-heating solid, inorganic, n.o.s. 4.2 UN3190 II, III Prohibited Prohibited

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

Self-heating solid, inorganic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Self-heating solid, organic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN3088, packing group II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-heating solid, organic, n.o.s. 4.2 UN3088 II, III Prohibited Prohibited

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

Self-heating solid, organic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Self-heating solid, oxidizing, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN3127, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-heating solid, oxidizing, n.o.s. 4.2 UN3127 n/a Prohibited Prohibited

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

Self-heating solid, oxidizing, n.o.s. — Postal shipping restrictions by item category


**Item category:** Self-heating solid, toxic, inorganic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN3191, packing group II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-heating solid, toxic, inorganic, n.o.s. 4.2 UN3191 II, III Prohibited Prohibited

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

Self-heating solid, toxic, inorganic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Self-heating solid, toxic, organic, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN3128, packing group II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-heating solid, toxic, organic, n.o.s. 4.2 UN3128 II, III Prohibited Prohibited

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

Self-heating solid, toxic, organic, n.o.s. — Postal shipping restrictions by item category


**Item category:** Self-reactive liquid type B, temperature controlled

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3231, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive liquid type B, temperature controlled 4.1 UN3231 II Prohibited Prohibited

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

Self-reactive liquid type B, temperature controlled — Postal shipping restrictions by item category


**Item category:** Self-reactive liquid type C, temperature controlled

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3233, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive liquid type C, temperature controlled 4.1 UN3233 II Prohibited Prohibited

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

Self-reactive liquid type C, temperature controlled — Postal shipping restrictions by item category


**Item category:** Self-reactive liquid type C

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3223, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive liquid type C 4.1 UN3223 II Prohibited Prohibited

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

Self-reactive liquid type C — Postal shipping restrictions by item category


**Item category:** Self-reactive liquid type D, temperature controlled

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3235, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive liquid type D, temperature controlled 4.1 UN3235 II Prohibited Prohibited

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

Self-reactive liquid type D, temperature controlled — Postal shipping restrictions by item category


**Item category:** Self-reactive liquid type D

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3225, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive liquid type D 4.1 UN3225 II Prohibited Prohibited

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

Self-reactive liquid type D — Postal shipping restrictions by item category


**Item category:** Self-reactive liquid type E, temperature controlled

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3237, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive liquid type E, temperature controlled 4.1 UN3237 II Prohibited Prohibited

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

Self-reactive liquid type E, temperature controlled — Postal shipping restrictions by item category


**Item category:** Self-reactive liquid type E

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3227, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive liquid type E 4.1 UN3227 II Prohibited Prohibited

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

Self-reactive liquid type E — Postal shipping restrictions by item category


**Item category:** Self-reactive liquid type F, temperature controlled

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3239, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive liquid type F, temperature controlled 4.1 UN3239 II Prohibited Prohibited

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

Self-reactive liquid type F, temperature controlled — Postal shipping restrictions by item category


**Item category:** Self-reactive liquid type F

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3229, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive liquid type F 4.1 UN3229 II Prohibited Prohibited

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

Self-reactive liquid type F — Postal shipping restrictions by item category


**Item category:** Self-reactive solid type B, temperature controlled

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3232, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive solid type B, temperature controlled 4.1 UN3232 II Prohibited Prohibited

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

Self-reactive solid type B, temperature controlled — Postal shipping restrictions by item category


**Item category:** Self-reactive solid type B

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3222, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive solid type B 4.1 UN3222 II Prohibited Prohibited

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

Self-reactive solid type B — Postal shipping restrictions by item category


**Item category:** Self-reactive solid type C, temperature controlled

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3234, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive solid type C, temperature controlled 4.1 UN3234 II Prohibited Prohibited

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

Self-reactive solid type C, temperature controlled — Postal shipping restrictions by item category


**Item category:** Self-reactive solid type C

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3224, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive solid type C 4.1 UN3224 II Prohibited Prohibited

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

Self-reactive solid type C — Postal shipping restrictions by item category


**Item category:** Self-reactive solid type D, temperature controlled

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3236, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive solid type D, temperature controlled 4.1 UN3236 II Prohibited Prohibited

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

Self-reactive solid type D, temperature controlled — Postal shipping restrictions by item category


**Item category:** Self-reactive solid type D

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3226, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive solid type D 4.1 UN3226 II Prohibited Prohibited

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

Self-reactive solid type D — Postal shipping restrictions by item category


**Item category:** Self-reactive solid type E, temperature controlled

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3238, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive solid type E, temperature controlled 4.1 UN3238 II Prohibited Prohibited

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

Self-reactive solid type E, temperature controlled — Postal shipping restrictions by item category


**Item category:** Self-reactive solid type E

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3228, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive solid type E 4.1 UN3228 II Prohibited Prohibited

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

Self-reactive solid type E — Postal shipping restrictions by item category


**Item category:** Self-reactive solid type F, temperature controlled

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3240, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive solid type F, temperature controlled 4.1 UN3240 II Prohibited Prohibited

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

Self-reactive solid type F, temperature controlled — Postal shipping restrictions by item category


**Item category:** Self-reactive solid type F

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3230, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Self-reactive solid type F 4.1 UN3230 II Prohibited Prohibited

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

Self-reactive solid type F — Postal shipping restrictions by item category


**Item category:** Shale Oil

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN1288, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Shale Oil 3 UN1288 I Prohibited Prohibited

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

Shale Oil — Postal shipping restrictions by item category


**Item category:** Sharps and regulated medical waste containing Category B infectious substance (UN3291)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic mail via USPS Ground Advantage only

**Conditions:** Permitted via USPS Returns Service via USPS Ground Advantage only; vendor must obtain prior authorization; strict packaging, testing, labeling requirements apply

> Regulated medical waste and sharps medical waste as defined in 346.12 ( f ) and 346.12 ( g ) and containing materials classified as Category B infectious substances must be marked UN3291 and are permitted for mailing only using USPS Returns Service (refer to DMM 505.3) via USPS Ground Advantage service.

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

Sharps and regulated medical waste containing Category B infectious substance (UN3291) — Postal shipping restrictions by item category


**Item category:** short-barreled rifles or shotguns - concealable

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all domestic mail

**Conditions:** Short-barreled rifles or shotguns that can be concealed on the person are nonmailable

> Short-barreled rifles or shotguns that can be concealed on the person are nonmailable.

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

short-barreled rifles or shotguns - concealable — Postal shipping restrictions by item category


**Item category:** Shotgun hulls, empty casings, nonmetallic shotgun hulls, or casings without primers

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** all domestic mail

**Conditions:** Not classified as explosives or hazardous materials under 49 CFR; mailable subject to applicable mailing rules

> Shotgun Hulls, Empty Casings, Nonmetallic Shotgun Hulls, or Casings Without Primers: These articles are not classified as explosives or hazardous materials under 49 CFR and, therefore, are mailable

Source: <https://pe.usps.com/text/pub52/pub52c3_020.htm>

Shotgun hulls, empty casings, nonmetallic shotgun hulls, or casings without primers — Postal shipping restrictions by item category


**Item category:** Signal devices, hand

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.4S, UN0373, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Signal devices, hand 1.4S UN0373 II Prohibited Prohibited

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

Signal devices, hand — Postal shipping restrictions by item category


**Item category:** Signals, distress, ship

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1G, UN0194, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Signals, distress, ship 1.1G UN0194 II Prohibited Prohibited

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

Signals, distress, ship — Postal shipping restrictions by item category


**Item category:** Signals, railway track, explosive

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1G, UN0192, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Signals, railway track, explosive 1.1G UN0192 II Prohibited Prohibited

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

Signals, railway track, explosive — Postal shipping restrictions by item category


**Item category:** Signals, smoke

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.2G, UN0313, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Signals, smoke 1.2G UN0313 II Prohibited Prohibited

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

Signals, smoke — Postal shipping restrictions by item category


**Item category:** Silane

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.1, UN2203, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Silane 2.1 UN2203 n/a Prohibited Prohibited

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

Silane — Postal shipping restrictions by item category


**Item category:** Silicon powder, amorphous

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN1346, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Silicon powder, amorphous 4.1 UN1346 III Prohibited Prohibited

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

Silicon powder, amorphous — Postal shipping restrictions by item category


**Item category:** Silicon tetrachloride

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1818, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Silicon tetrachloride 8 UN1818 II 8A 8A

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

Silicon tetrachloride — Postal shipping restrictions by item category


**Item category:** Silicon tetrafluoride, compressed

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1859, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Silicon tetrafluoride, compressed 2.3 UN1859 n/a Prohibited Prohibited

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

Silicon tetrafluoride, compressed — Postal shipping restrictions by item category


**Item category:** Silver acetylide (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.

> Silver acetylide (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Silver acetylide (dry) — Postal shipping restrictions by item category


**Item category:** Silver arsenite

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1683, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Silver arsenite 6.1 UN1683 II Prohibited Prohibited

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

Silver arsenite — Postal shipping restrictions by item category


**Item category:** Silver 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.

> Silver azide (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

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


**Item category:** Silver chlorite (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.

> Silver chlorite (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Silver chlorite (dry) — Postal shipping restrictions by item category


**Item category:** Silver cyanide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1684, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Silver cyanide 6.1 UN1684 II Prohibited Prohibited

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

Silver cyanide — Postal shipping restrictions by item category


**Item category:** Silver fulminate (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.

> Prohibited Silver fulminate (dry)

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

Silver fulminate (dry) — Postal shipping restrictions by item category


**Item category:** Silver nitrate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1493, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Silver nitrate 5.1 UN1493 II 5A 5A

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

Silver nitrate — Postal shipping restrictions by item category


**Item category:** Silver oxalate (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.

> Silver oxalate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Silver oxalate (dry) — Postal shipping restrictions by item category


**Item category:** Silver 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.

> Silver picrate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

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


**Item category:** Silver picrate, wetted with not less than 30 percent water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN1347, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Silver picrate, wetted with not less than 30 percent water, by mass 4.1 UN1347 I Prohibited Prohibited

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

Silver picrate, wetted with not less than 30 percent water, by mass — Postal shipping restrictions by item category


**Item category:** Sludge, acid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1906, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sludge, acid 8 UN1906 II Prohibited Prohibited

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

Sludge, acid — Postal shipping restrictions by item category


**Item category:** Small Arms Ammunition regulated as Class 1 explosive

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Ammunition regulated as Class 1 explosive fired from pistol, revolver, rifle, or shotgun; associated primers, blank cartridges, and propellant powder are prohibited

> Ammunition that is regulated as a Class 1 explosive and designed to be fired from a pistol, revolver, rifle, or shotgun, as well as associated primers and blank cartridges (including those designed for tools) and propellant powder for use in any firearm, is prohibited from mailing.

Source: <https://pe.usps.com/text/pub52/pub52c3_020.htm>

Small Arms Ammunition regulated as Class 1 explosive — Postal shipping restrictions by item category


**Item category:** Small consumer-type lithium-ion batteries in equipment (up to 20 Wh per cell, 100 Wh per battery)

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Mailable via air and surface; cells not to exceed 20 Wh, batteries not to exceed 100 Wh; up to 8 cells or 2 batteries per mailpiece; must display DOT-approved lithium battery mark

> Small consumer-type lithium-ion cells and batteries (also called secondary lithium cells or batteries), such as those used to power cell phones and laptop computers, are only mailable domestically under the following conditions.

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

Small consumer-type lithium-ion batteries in equipment (up to 20 Wh per cell, 100 Wh per battery) — Postal shipping restrictions by item category


**Item category:** Small consumer-type lithium metal batteries in equipment (up to 1g per cell, 2g per battery)

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Mailable via air and surface; cells not to exceed 1g lithium, batteries not to exceed 2g lithium; up to 8 cells or 2 batteries per mailpiece; must display DOT-approved lithium battery mark

> Small consumer-type lithium metal cells or batteries (also called primary lithium cells or batteries), such as those used to power cameras or flashlights, are mailable domestically under the following conditions.

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

Small consumer-type lithium metal batteries in equipment (up to 1g per cell, 2g per battery) — Postal shipping restrictions by item category

carrier, conditions, item_category, restriction_type


**Item category:** small harmless cold-blooded animals (except snakes, turtles, turtle eggs)

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** domestic mail

**Conditions:** Mailable only when they meet specific requirements including ability to reach destination in good condition, not requiring food or water (except fish), not creating sanitary problems or obnoxious odors; includes baby alligators, chameleons, frogs, lizards, newts, salamanders, tadpoles, goldfish, tropical fish, worms, leeches, snails, and nonpoisonous insects

> Small, harmless, cold-blooded animals, except for snakes, turtles, and turtle eggs, are mailable only when they meet requirements specified in Exhibit 526.6

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

small harmless cold-blooded animals (except snakes, turtles, turtle eggs) — Postal shipping restrictions by item category

carrier, conditions, restriction_type, scope


**Item category:** Smokeless powder for small arms (100 pounds or less)

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, NA3178, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Smokeless powder for small arms (100 pounds or less) 4.1 NA3178 I Prohibited Prohibited

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

Smokeless powder for small arms (100 pounds or less) — Postal shipping restrictions by item category


**Item category:** smokeless tobacco

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** all domestic mail

**Conditions:** Any finely cut, ground, powdered, or leaf tobacco intended to be placed in the oral or nasal cavity or otherwise consumed without combustion

> Smokeless Tobacco: Any finely cut, ground, powdered, or leaf tobacco intended to be placed in the oral or nasal cavity or otherwise consumed without combustion.

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

smokeless tobacco — Postal shipping restrictions by item category


**Item category:** snakes, turtles, and poisonous reptiles

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all domestic mail

**Conditions:** All snakes, turtles, and poisonous reptiles are nonmailable

> All snakes, turtles, and poisonous reptiles are nonmailable.

Source: <https://pe.usps.com/text/pub52/pub52c5_008.htm>

snakes, turtles, and poisonous reptiles — Postal shipping restrictions by item category


**Item category:** Soda lime with more than 4 percent sodium hydroxide

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1907, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Soda lime with more than 4 percent sodium hydroxide 8 UN1907 III 8A 8A

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

Soda lime with more than 4 percent sodium hydroxide — Postal shipping restrictions by item category


**Item category:** Sodium aluminate, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2812, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Sodium aluminate, solid 8 UN2812 III 8A 8A

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

Sodium aluminate, solid — Postal shipping restrictions by item category


**Item category:** Sodium aluminate, solution

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1819, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Sodium aluminate, solution 8 UN1819 II, III 8A 8A

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

Sodium aluminate, solution — Postal shipping restrictions by item category


**Item category:** Sodium aluminum hydride

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.3, UN2835, packing group II; domestic mail air: Prohibited; domestic mail surface: 4A

> Sodium aluminum hydride 4.3 UN2835 II Prohibited 4A

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

Sodium aluminum hydride — Postal shipping restrictions by item category


**Item category:** Sodium ammonium vanadate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2863, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium ammonium vanadate 6.1 UN2863 II Prohibited Prohibited

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

Sodium ammonium vanadate — Postal shipping restrictions by item category


**Item category:** Sodium arsanilate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2473, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Sodium arsanilate 6.1 UN2473 III 6A 6A

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

Sodium arsanilate — Postal shipping restrictions by item category


**Item category:** Sodium arsenate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1685, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium arsenate 6.1 UN1685 II Prohibited Prohibited

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

Sodium arsenate — Postal shipping restrictions by item category


**Item category:** Sodium arsenite, aqueous solutions

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1686, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium arsenite, aqueous solutions 6.1 UN1686 II Prohibited Prohibited

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

Sodium arsenite, aqueous solutions — Postal shipping restrictions by item category


**Item category:** Sodium arsenite, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2027, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium arsenite, solid 6.1 UN2027 II Prohibited Prohibited

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

Sodium arsenite, solid — Postal shipping restrictions by item category


**Item category:** Sodium azide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1687, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium azide 6.1 UN1687 II Prohibited Prohibited

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

Sodium azide — Postal shipping restrictions by item category


**Item category:** Sodium borohydride and sodium hydroxide solution, with not more than 12 percent sodium borohydride and not more than 40 percent sodium hydroxide by mass

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN3320, packing group II, III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium borohydride and sodium hydroxide solution, with not more than 12 percent sodium borohydride and not more than 40 percent sodium hydroxide by mass 8 UN3320 II, III Prohibited Prohibited

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

Sodium borohydride and sodium hydroxide solution, with not more than 12 percent sodium borohydride and not more than 40 percent sodium hydroxide by mass — Postal shipping restrictions by item category


**Item category:** Sodium borohydride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN1426, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium borohydride 4.3 UN1426 I Prohibited Prohibited

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

Sodium borohydride — Postal shipping restrictions by item category


**Item category:** Sodium bromate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1494, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Sodium bromate 5.1 UN1494 II 5A 5A

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

Sodium bromate — Postal shipping restrictions by item category


**Item category:** Sodium cacodylate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1688, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium cacodylate 6.1 UN1688 II Prohibited Prohibited

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

Sodium cacodylate — Postal shipping restrictions by item category


**Item category:** Sodium carbonate peroxyhydrate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN3378, packing group II, III; domestic mail air: 5A; domestic mail surface: 5A

> Sodium carbonate peroxyhydrate 5.1 UN3378 II, III 5A 5A

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

Sodium carbonate peroxyhydrate — Postal shipping restrictions by item category


**Item category:** Sodium chlorate, aqueous solution

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN2428, packing group II, III; domestic mail air: 5A; domestic mail surface: 5A

> Sodium chlorate, aqueous solution 5.1 UN2428 II, III 5A 5A

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

Sodium chlorate, aqueous solution — Postal shipping restrictions by item category


**Item category:** Sodium chlorate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1495, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Sodium chlorate 5.1 UN1495 II 5A 5A

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

Sodium chlorate — Postal shipping restrictions by item category


**Item category:** Sodium chlorite

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, UN1496, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium chlorite 5.1 UN1496 II Prohibited Prohibited

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

Sodium chlorite — Postal shipping restrictions by item category


**Item category:** Sodium chlorite

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Nonmailable Division 5.1 oxidizing substance

> Sodium chlorite.

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


**Item category:** Sodium chloroacetate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2659, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Sodium chloroacetate 6.1 UN2659 III 6A 6A

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

Sodium chloroacetate — Postal shipping restrictions by item category


**Item category:** Sodium cuprocyanide, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2316, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium cuprocyanide, solid 6.1 UN2316 I Prohibited Prohibited

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

Sodium cuprocyanide, solid — Postal shipping restrictions by item category


**Item category:** Sodium cuprocyanide, solution

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2317, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium cuprocyanide, solution 6.1 UN2317 I Prohibited Prohibited

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

Sodium cuprocyanide, solution — Postal shipping restrictions by item category


**Item category:** Sodium cyanide, solid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1689, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium cyanide, solid 6.1 UN1689 I Prohibited Prohibited

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

Sodium cyanide, solid — Postal shipping restrictions by item category


**Item category:** Sodium cyanide, solution

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3414, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium cyanide, solution 6.1 UN3414 I, II Prohibited Prohibited

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

Sodium cyanide, solution — Postal shipping restrictions by item category


**Item category:** Sodium dinitro-o-cresolate, wetted with not less than 10 percent water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN3369, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium dinitro-o-cresolate, wetted with not less than 10 percent water, by mass 4.1 UN3369 I Prohibited Prohibited

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

Sodium dinitro-o-cresolate, wetted with not less than 10 percent water, by mass — Postal shipping restrictions by item category


**Item category:** Sodium dinitro-o-cresolate, wetted with not less than 15 percent water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN1348, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium dinitro-o-cresolate, wetted with not less than 15 percent water, by mass 4.1 UN1348 I Prohibited Prohibited

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

Sodium dinitro-o-cresolate, wetted with not less than 15 percent water, by mass — Postal shipping restrictions by item category


**Item category:** Sodium dithionite or Sodium hydrosulfite

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN1384, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium dithionite or Sodium hydrosulfite 4.2 UN1384 II Prohibited Prohibited

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

Sodium dithionite or Sodium hydrosulfite — Postal shipping restrictions by item category


**Item category:** Sodium fluoride, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN1690, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Sodium fluoride, solid 6.1 UN1690 III 6A 6A

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

Sodium fluoride, solid — Postal shipping restrictions by item category


**Item category:** Sodium fluoride, solution

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN3415, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Sodium fluoride, solution 6.1 UN3415 III 6A 6A

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

Sodium fluoride, solution — Postal shipping restrictions by item category


**Item category:** Sodium fluoroacetate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2629, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium fluoroacetate 6.1 UN2629 I Prohibited Prohibited

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

Sodium fluoroacetate — Postal shipping restrictions by item category


**Item category:** Sodium fluorosilicate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2674, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Sodium fluorosilicate 6.1 UN2674 III 6A 6A

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

Sodium fluorosilicate — Postal shipping restrictions by item category


**Item category:** Sodium hydride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN1427, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium hydride 4.3 UN1427 I Prohibited Prohibited

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

Sodium hydride — Postal shipping restrictions by item category


**Item category:** Sodium hydrogendifluoride

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2439, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Sodium hydrogendifluoride 8 UN2439 II 8A 8A

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

Sodium hydrogendifluoride — Postal shipping restrictions by item category


**Item category:** Sodium hydrosulfide, with less than 25 percent water of crystallization

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN2318, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium hydrosulfide, with less than 25 percent water of crystallization 4.2 UN2318 II Prohibited Prohibited

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

Sodium hydrosulfide, with less than 25 percent water of crystallization — Postal shipping restrictions by item category


**Item category:** Sodium hydrosulfide, with not less than 25 percent water of crystallization

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN2949, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium hydrosulfide, with not less than 25 percent water of crystallization 8 UN2949 II Prohibited Prohibited

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

Sodium hydrosulfide, with not less than 25 percent water of crystallization — Postal shipping restrictions by item category


**Item category:** Sodium hydroxide, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1823, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Sodium hydroxide, solid 8 UN1823 II 8A 8A

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

Sodium hydroxide, solid — Postal shipping restrictions by item category


**Item category:** Sodium hydroxide solution

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1824, packing group II, III; domestic mail air: 8A; domestic mail surface: 8A

> Sodium hydroxide solution 8 UN1824 II, III 8A 8A

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

Sodium hydroxide solution — Postal shipping restrictions by item category


**Item category:** Sodium methylate solutions in alcohol

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN1289, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium methylate solutions in alcohol 3 UN1289 II Prohibited Prohibited

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

Sodium methylate solutions in alcohol — Postal shipping restrictions by item category


**Item category:** Sodium methylate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN1431, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium methylate 4.2 UN1431 II Prohibited Prohibited

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

Sodium methylate — Postal shipping restrictions by item category


**Item category:** Sodium monoxide

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1825, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Sodium monoxide 8 UN1825 II 8A 8A

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

Sodium monoxide — Postal shipping restrictions by item category


**Item category:** Sodium nitrate and potassium nitrate mixtures

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1499, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Sodium nitrate and potassium nitrate mixtures 5.1 UN1499 III 5A 5A

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

Sodium nitrate and potassium nitrate mixtures — Postal shipping restrictions by item category


**Item category:** Sodium nitrate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1498, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Sodium nitrate 5.1 UN1498 III 5A 5A

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

Sodium nitrate — Postal shipping restrictions by item category


**Item category:** Sodium nitrite

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1500, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Sodium nitrite 5.1 UN1500 III 5A 5A

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

Sodium nitrite — Postal shipping restrictions by item category


**Item category:** Sodium pentachlorophenate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2567, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium pentachlorophenate 6.1 UN2567 II Prohibited Prohibited

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

Sodium pentachlorophenate — Postal shipping restrictions by item category


**Item category:** Sodium perborate monohydrate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN3377, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Sodium perborate monohydrate 5.1 UN3377 III 5A 5A

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

Sodium perborate monohydrate — Postal shipping restrictions by item category


**Item category:** Sodium perchlorate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1502, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Sodium perchlorate 5.1 UN1502 II 5A 5A

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

Sodium perchlorate — Postal shipping restrictions by item category


**Item category:** Sodium permanganate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1503, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Sodium permanganate 5.1 UN1503 II 5A 5A

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

Sodium permanganate — Postal shipping restrictions by item category


**Item category:** Sodium peroxide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, UN1504, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium peroxide 5.1 UN1504 I Prohibited Prohibited

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

Sodium peroxide — Postal shipping restrictions by item category


**Item category:** Sodium peroxoborate, anhydrous

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN3247, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Sodium peroxoborate, anhydrous 5.1 UN3247 II 5A 5A

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

Sodium peroxoborate, anhydrous — Postal shipping restrictions by item category


**Item category:** Sodium persulfate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1505, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Sodium persulfate 5.1 UN1505 III 5A 5A

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

Sodium persulfate — Postal shipping restrictions by item category


**Item category:** Sodium phosphide

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.3, UN1432, packing group I; domestic mail air: Prohibited; domestic mail surface: 4A

> Sodium phosphide 4.3 UN1432 I Prohibited 4A

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

Sodium phosphide — Postal shipping restrictions by item category


**Item category:** Sodium picramate, dry or wetted with less than 20 percent water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.3C, UN0235, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium picramate, dry or wetted with less than 20 percent water, by mass 1.3C UN0235 II Prohibited Prohibited

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

Sodium picramate, dry or wetted with less than 20 percent water, by mass — Postal shipping restrictions by item category


**Item category:** Sodium picramate, wetted with not less than 20 percent water, by mass

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.1, UN1349, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium picramate, wetted with not less than 20 percent water, by mass 4.1 UN1349 I Prohibited Prohibited

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

Sodium picramate, wetted with not less than 20 percent water, by mass — Postal shipping restrictions by item category


**Item category:** Sodium picryl peroxide

**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.

> Sodium picryl peroxide Forbidden Prohibited Prohibited Prohibited Prohibited

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

Sodium picryl peroxide — Postal shipping restrictions by item category


**Item category:** Sodium sulfide, anhydrous or Sodium sulfide with less than 30 percent water of crystallization

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN1385, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium sulfide, anhydrous or Sodium sulfide with less than 30 percent water of crystallization 4.2 UN1385 II Prohibited Prohibited

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

Sodium sulfide, anhydrous or Sodium sulfide with less than 30 percent water of crystallization — Postal shipping restrictions by item category


**Item category:** Sodium sulfide, hydrated with not less than 30 percent water

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1849, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium sulfide, hydrated with not less than 30 percent water 8 UN1849 II Prohibited Prohibited

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

Sodium sulfide, hydrated with not less than 30 percent water — Postal shipping restrictions by item category


**Item category:** Sodium superoxide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, UN2547, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium superoxide 5.1 UN2547 I Prohibited Prohibited

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

Sodium superoxide — Postal shipping restrictions by item category


**Item category:** Sodium tetranitride

**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.

> Sodium tetranitride Forbidden Prohibited Prohibited Prohibited Prohibited

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

Sodium tetranitride — Postal shipping restrictions by item category


**Item category:** Sodium

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN1428, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sodium 4.3 UN1428 I Prohibited Prohibited

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

Sodium — Postal shipping restrictions by item category


**Item category:** Solids containing corrosive liquid, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN3244, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Solids containing corrosive liquid, n.o.s. 8 UN3244 II 8A 8A

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

Solids containing corrosive liquid, n.o.s. — Postal shipping restrictions by item category


**Item category:** Solids containing flammable liquid, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 4.1, UN3175, packing group II; domestic mail air: Prohibited; domestic mail surface: 4A

> Solids containing flammable liquid, n.o.s. 4.1 UN3175 II Prohibited 4A

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

Solids containing flammable liquid, n.o.s. — Postal shipping restrictions by item category


**Item category:** Solids containing toxic liquid, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3243, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Solids containing toxic liquid, n.o.s. 6.1 UN3243 II Prohibited Prohibited

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

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


**Item category:** Sounding devices, explosive

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1D, UN0374, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sounding devices, explosive 1.1D UN0374 II Prohibited Prohibited

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

Sounding devices, explosive — Postal shipping restrictions by item category


**Item category:** Spray paint (aerosol)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic US

**Conditions:** Classified as flammable aerosol. Requires hazmat declaration and rigid outer packaging. $50 noncompliance fee if undeclared, effective July 12, 2026.

> Spray paint | Flammable aerosol | UN1950

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

Spray paint (aerosol) — Postal shipping restrictions by item category

carrier, conditions, item_category, restriction_type, scope


**Item category:** Stannic chloride, anhydrous

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1827, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Stannic chloride, anhydrous 8 UN1827 II 8A 8A

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

Stannic chloride, anhydrous — Postal shipping restrictions by item category


**Item category:** Stannic chloride, pentahydrate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2440, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Stannic chloride, pentahydrate 8 UN2440 III 8A 8A

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

Stannic chloride, pentahydrate — Postal shipping restrictions by item category


**Item category:** Stannic phosphide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN1433, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Stannic phosphide 4.3 UN1433 I Prohibited Prohibited

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

Stannic phosphide — Postal shipping restrictions by item category


**Item category:** Strike-anywhere matches

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Strike-anywhere matches are nonmailable flammable solids

> Strike-anywhere matches and safety matches are examples of flammable solids. All flammable solids are prohibited in domestic air transportation and in international mail.

Source: <https://pe.usps.com/text/pub52/pub52c3_023.htm>

Strike-anywhere matches — Postal shipping restrictions by item category


**Item category:** Strike-Anywhere Matches

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** domestic

**Conditions:** Strike-anywhere matches may not be mailed domestically.

> Strike-anywhere matches may not be mailed domestically.

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

Strike-Anywhere Matches — Postal shipping restrictions by item category


**Item category:** Strong magnets (rare-earth, magnetic phone mounts, certain speakers, magnetic toys)

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** domestic US

**Conditions:** Classified as hazardous due to magnetic field strength. Requires hazmat declaration. $50 noncompliance fee if undeclared, effective July 12, 2026.

> Strong magnets — rare-earth magnets, magnetic phone mounts, certain speakers, magnetic toys

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

Strong magnets (rare-earth, magnetic phone mounts, certain speakers, magnetic toys) — Postal shipping restrictions by item category


**Item category:** Strontium chlorate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1506, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Strontium chlorate 5.1 UN1506 II 5A 5A

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

Strontium chlorate — Postal shipping restrictions by item category


**Item category:** Strontium nitrate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1507, packing group III; domestic mail air: 5A; domestic mail surface: 5A

> Strontium nitrate 5.1 UN1507 III 5A 5A

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

Strontium nitrate — Postal shipping restrictions by item category


**Item category:** Strontium perchlorate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1508, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Strontium perchlorate 5.1 UN1508 II 5A 5A

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

Strontium perchlorate — Postal shipping restrictions by item category


**Item category:** Strontium peroxide

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 5.1, UN1509, packing group II; domestic mail air: 5A; domestic mail surface: 5A

> Strontium peroxide 5.1 UN1509 II 5A 5A

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

Strontium peroxide — Postal shipping restrictions by item category


**Item category:** Strontium phosphide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.3, UN2013, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Strontium phosphide 4.3 UN2013 I Prohibited Prohibited

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

Strontium phosphide — Postal shipping restrictions by item category


**Item category:** Strychnine or Strychnine salts

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1692, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Strychnine or Strychnine salts 6.1 UN1692 I Prohibited Prohibited

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

Strychnine or Strychnine salts — Postal shipping restrictions by item category


**Item category:** Substances, explosive, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1A, UN0473, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Substances, explosive, n.o.s. 1.1A UN0473 II Prohibited Prohibited

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

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


**Item category:** Substances, explosive, very insensitive, n.o.s., or Substances, EVI, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.5D, UN0482, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Substances, explosive, very insensitive, n.o.s., or Substances, EVI, n.o.s. 1.5D UN0482 II Prohibited Prohibited

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

Substances, explosive, very insensitive, n.o.s., or Substances, EVI, n.o.s. — Postal shipping restrictions by item category


**Item category:** Substituted nitrophenol pesticides, liquid, flammable, toxic, flashpoint less than 23° C

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN2780, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Substituted nitrophenol pesticides, liquid, flammable, toxic, flashpoint less than 23° C 3 UN2780 I, II Prohibited Prohibited

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

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


**Item category:** Substituted nitrophenol 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, UN3013, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Substituted nitrophenol pesticides, liquid, toxic flammable flashpoint not less than 23° C 6.1 UN3013 I, II Prohibited Prohibited

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

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


**Item category:** Substituted nitrophenol pesticides, liquid, toxic

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3014, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Substituted nitrophenol pesticides, liquid, toxic 6.1 UN3014 I, II Prohibited Prohibited

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

Substituted nitrophenol pesticides, liquid, toxic — Postal shipping restrictions by item category


**Item category:** Substituted nitrophenol pesticides, solid, toxic

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2779, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Substituted nitrophenol pesticides, solid, toxic 6.1 UN2779 I, II Prohibited Prohibited

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

Substituted nitrophenol pesticides, solid, toxic — Postal shipping restrictions by item category


**Item category:** Sucrose octanitrate (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.

> Sucrose octanitrate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Sucrose octanitrate (dry) — Postal shipping restrictions by item category


**Item category:** Sulfamic acid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2967, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Sulfamic acid 8 UN2967 III 8A 8A

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

Sulfamic acid — Postal shipping restrictions by item category


**Item category:** Sulfur and chlorate, loose mixtures of

**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.

> Sulfur and chlorate, loose mixtures of Forbidden Prohibited Prohibited Prohibited Prohibited

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

Sulfur and chlorate, loose mixtures of — Postal shipping restrictions by item category


**Item category:** Sulfur chlorides

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1828, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfur chlorides 8 UN1828 I Prohibited Prohibited

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

Sulfur chlorides — Postal shipping restrictions by item category


**Item category:** Sulfur dioxide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN1079, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfur dioxide 2.3 UN1079 n/a Prohibited Prohibited

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

Sulfur dioxide — Postal shipping restrictions by item category


**Item category:** Sulfur hexafluoride

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.2, UN1080, packing group n/a; domestic mail air: 2B; domestic mail surface: 2B

> Sulfur hexafluoride 2.2 UN1080 n/a 2B 2B

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

Sulfur hexafluoride — Postal shipping restrictions by item category


**Item category:** Sulfur, molten

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 9, NA2448, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfur, molten 9 NA2448 III Prohibited Prohibited

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

Sulfur, molten — Postal shipping restrictions by item category


**Item category:** Sulfur tetrafluoride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN2418, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfur tetrafluoride 2.3 UN2418 n/a Prohibited Prohibited

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

Sulfur tetrafluoride — Postal shipping restrictions by item category


**Item category:** Sulfur trioxide, stabilized

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1829, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfur trioxide, stabilized 8 UN1829 I Prohibited Prohibited

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

Sulfur trioxide, stabilized — Postal shipping restrictions by item category


**Item category:** Sulfur

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 9, NA1350, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfur 9 NA1350 III Prohibited Prohibited

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

Sulfur — Postal shipping restrictions by item category


**Item category:** Sulfuric acid, fuming with 30 percent or more free sulfur trioxide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1831, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfuric acid, fuming with 30 percent or more free sulfur trioxide 8 UN1831 I Prohibited Prohibited

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

Sulfuric acid, fuming with 30 percent or more free sulfur trioxide — Postal shipping restrictions by item category


**Item category:** Sulfuric acid, fuming with less than 30 percent free sulfur trioxide

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1831, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfuric acid, fuming with less than 30 percent free sulfur trioxide 8 UN1831 I Prohibited Prohibited

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

Sulfuric acid, fuming with less than 30 percent free sulfur trioxide — Postal shipping restrictions by item category


**Item category:** Sulfuric acid, spent

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1832, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfuric acid, spent 8 UN1832 II Prohibited Prohibited

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

Sulfuric acid, spent — Postal shipping restrictions by item category


**Item category:** Sulfuric acid (UN2796)

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Acceptable only in solutions of 25% or less acid that qualify as Limited Quantity air or surface; Packaging Instruction 8A must be followed

> Sulfuric Acid (UN2796): Acceptable only in solutions of 25 percent or less acid that can qualify as a Limited Quantity air or Limited Quantity surface material.

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

Sulfuric acid (UN2796) — Postal shipping restrictions by item category


**Item category:** Sulfuric acid with more than 51 percent acid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1830, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfuric acid with more than 51 percent acid 8 UN1830 II Prohibited Prohibited

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

Sulfuric acid with more than 51 percent acid — Postal shipping restrictions by item category


**Item category:** Sulfuric acid with not more than 51 percent acid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2796, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Sulfuric acid with not more than 51 percent acid 8 UN2796 II 8A 8A

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

Sulfuric acid with not more than 51 percent acid — Postal shipping restrictions by item category


**Item category:** Sulfurous acid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1833, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Sulfurous acid 8 UN1833 II 8A 8A

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

Sulfurous acid — Postal shipping restrictions by item category


**Item category:** Sulfuryl chloride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 8, UN1834, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfuryl chloride 8 UN1834 I Prohibited Prohibited

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

Sulfuryl chloride — Postal shipping restrictions by item category


**Item category:** Sulfuryl fluoride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN2191, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Sulfuryl fluoride 2.3 UN2191 n/a Prohibited Prohibited

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

Sulfuryl fluoride — Postal shipping restrictions by item category


**Item category:** switchblade knife - manufacturer or dealer to authorized recipients

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** domestic mail - from authorized manufacturers or dealers to authorized recipients

**Conditions:** Authorized manufacturers or bona fide dealers may mail switchblade knives to government procurement officials or authorized recipients in connection with official procurement or resale

> Authorized manufacturers or bona fide dealers may mail switchblade knives to addresses within one of the categories listed above in connection with official procurement or resale.

Source: <https://pe.usps.com/text/pub52/pub52c4_015.htm>

switchblade knife - manufacturer or dealer to authorized recipients — Postal shipping restrictions by item category


**Item category:** switchblade knife - to government procurement officials

**Carrier:** USPS

**Restriction type:** allowed

**Scope:** domestic mail - to government supply or procurement officials only

**Conditions:** Mailable only to designated government officers or employees ordering or procuring switchblade knives in connection with government activities, including federal civilian and armed forces, National Guard, Air National Guard, militia, and municipal government supply or procurement officers

> Government Supply or Procurement Officials: Designated officers or employees ordering, procuring, or purchasing switchblade knives in connection with the activities of their respective governments or organizations

Source: <https://pe.usps.com/text/pub52/pub52c4_015.htm>

switchblade knife - to government procurement officials — Postal shipping restrictions by item category


**Item category:** switchblade knife

**Carrier:** USPS

**Restriction type:** restricted

**Scope:** all domestic mail

**Conditions:** A switchblade knife features a blade that opens automatically by hand pressure applied to a button or other device on the handle, or through inertia, gravity, or both; mailable only to specific government and manufacturer recipients

> A switchblade knife features a blade that opens automatically by hand pressure applied to a button or other device on the handle, or through inertia, gravity, or both.

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

switchblade knife — Postal shipping restrictions by item category


**Item category:** Tars, liquid including road oils and cutback, bitumens

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1999, packing group II, III; domestic mail air: Prohibited; domestic mail surface: 3A

> Tars, liquid including road oils and cutback, bitumens 3 UN1999 II, III Prohibited 3A

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

Tars, liquid including road oils and cutback, bitumens — Postal shipping restrictions by item category


**Item category:** Tear gas candles

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1700, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tear gas candles 6.1 UN1700 II Prohibited Prohibited

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

Tear gas candles — Postal shipping restrictions by item category


**Item category:** Tear gas substances, liquid, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1693, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tear gas substances, liquid, n.o.s. 6.1 UN1693 I, II Prohibited Prohibited

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

Tear gas substances, liquid, n.o.s. — Postal shipping restrictions by item category


**Item category:** Tear gas substances, solid, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3448, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tear gas substances, solid, n.o.s. 6.1 UN3448 I, II Prohibited Prohibited

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

Tear gas substances, solid, n.o.s. — Postal shipping restrictions by item category


**Item category:** Tear gas

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Nonmailable irritating material; exceptions may exist for those containing oleoresin capsicum

> Tear gas (UN1700, NA1693, and UN1693), except for those containing oleoresin capsicum.

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

Tear gas — Postal shipping restrictions by item category


**Item category:** Tellurium compound, n.o.s.

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN3284, packing group I, II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tellurium compound, n.o.s. 6.1 UN3284 I, II Prohibited Prohibited

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

Tellurium compound, n.o.s. — Postal shipping restrictions by item category


**Item category:** Tellurium hexafluoride

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.3, UN2195, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tellurium hexafluoride 2.3 UN2195 n/a Prohibited Prohibited

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

Tellurium hexafluoride — Postal shipping restrictions by item category


**Item category:** Terpene hydrocarbons, n.o.s.

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2319, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Terpene hydrocarbons, n.o.s. 3 UN2319 III Prohibited 3A

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

Terpene hydrocarbons, n.o.s. — Postal shipping restrictions by item category


**Item category:** Terpinolene

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2541, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Terpinolene 3 UN2541 III Prohibited 3A

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

Terpinolene — Postal shipping restrictions by item category


**Item category:** Tert-Butoxycarbonyl 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.

> Tert-Butoxycarbonyl azide Forbidden Prohibited Prohibited Prohibited Prohibited

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

Tert-Butoxycarbonyl azide — Postal shipping restrictions by item category


**Item category:** Tert-Butyl hydroperoxide, with more than 90 percent with water

**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.

> Tert-Butyl hydroperoxide, with more than 90 percent with water Forbidden Prohibited Prohibited Prohibited Prohibited

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

Tert-Butyl hydroperoxide, with more than 90 percent with water — Postal shipping restrictions by item category


**Item category:** Tert-Butyl hypochlorite

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 4.2, UN3255, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tert-Butyl hypochlorite 4.2 UN3255 I Prohibited Prohibited

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

Tert-Butyl hypochlorite — Postal shipping restrictions by item category


**Item category:** Tert-Butyl isocyanate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN2484, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tert-Butyl isocyanate 6.1 UN2484 I Prohibited Prohibited

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

Tert-Butyl isocyanate — Postal shipping restrictions by item category


**Item category:** tert-Butyl peroxyacetate, with more than 76 percent in solution

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> tert-Butyl peroxyacetate, with more than 76 percent in solution Forbidden Prohibited Prohibited Prohibited Prohibited

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

tert-Butyl peroxyacetate, with more than 76 percent in solution — Postal shipping restrictions by item category


**Item category:** tert-Butyl peroxyisobutyrate, with more than 77 percent in solution

**Carrier:** USPS

**Restriction type:** prohibited

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

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

> tert-Butyl peroxyisobutyrate, with more than 77 percent in solution Forbidden Prohibited Prohibited Prohibited Prohibited

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

tert-Butyl peroxyisobutyrate, with more than 77 percent in solution — Postal shipping restrictions by item category


**Item category:** tert-Butylcyclohexylchloroformate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2747, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> tert-Butylcyclohexylchloroformate 6.1 UN2747 III 6A 6A

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

tert-Butylcyclohexylchloroformate — Postal shipping restrictions by item category


**Item category:** Tetraazido benzene quinone

**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.

> Tetraazido benzene quinone Forbidden Prohibited Prohibited Prohibited Prohibited

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

Tetraazido benzene quinone — Postal shipping restrictions by item category


**Item category:** Tetrabromoethane

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN2504, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Tetrabromoethane 6.1 UN2504 III 6A 6A

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

Tetrabromoethane — Postal shipping restrictions by item category


**Item category:** Tetrachloroethylene

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 6.1, UN1897, packing group III; domestic mail air: 6A; domestic mail surface: 6A

> Tetrachloroethylene 6.1 UN1897 III 6A 6A

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

Tetrachloroethylene — Postal shipping restrictions by item category


**Item category:** Tetraethyl dithiopyrophosphate

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 6.1, UN1704, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tetraethyl dithiopyrophosphate 6.1 UN1704 II Prohibited Prohibited

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

Tetraethyl dithiopyrophosphate — Postal shipping restrictions by item category


**Item category:** Tetraethyl silicate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN1292, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Tetraethyl silicate 3 UN1292 III Prohibited 3A

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

Tetraethyl silicate — Postal shipping restrictions by item category


**Item category:** Tetraethylammonium perchlorate (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.

> Tetraethylammonium perchlorate (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Tetraethylammonium perchlorate (dry) — Postal shipping restrictions by item category


**Item category:** Tetraethylenepentamine

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2320, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Tetraethylenepentamine 8 UN2320 III 8A 8A

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

Tetraethylenepentamine — Postal shipping restrictions by item category


**Item category:** Tetrafluoroethylene, stabilized

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 2.1, UN1081, packing group n/a; domestic mail air: Prohibited; domestic mail surface: 2A

> Tetrafluoroethylene, stabilized 2.1 UN1081 n/a Prohibited 2A

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

Tetrafluoroethylene, stabilized — Postal shipping restrictions by item category


**Item category:** Tetrafluoromethane or Refrigerant gas R 14

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 2.2, UN1982, packing group n/a; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tetrafluoromethane or Refrigerant gas R 14 2.2 UN1982 n/a Prohibited Prohibited

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

Tetrafluoromethane or Refrigerant gas R 14 — Postal shipping restrictions by item category


**Item category:** Tetrahydrofuran

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN2056, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tetrahydrofuran 3 UN2056 II Prohibited Prohibited

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

Tetrahydrofuran — Postal shipping restrictions by item category


**Item category:** Tetrahydrofurfurylamine

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2943, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Tetrahydrofurfurylamine 3 UN2943 III Prohibited 3A

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

Tetrahydrofurfurylamine — Postal shipping restrictions by item category


**Item category:** Tetrahydrophthalic anhydrides with more than 0.05 percent of maleic anhydride

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN2698, packing group III; domestic mail air: 8A; domestic mail surface: 8A

> Tetrahydrophthalic anhydrides with more than 0.05 percent of maleic anhydride 8 UN2698 III 8A 8A

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

Tetrahydrophthalic anhydrides with more than 0.05 percent of maleic anhydride — Postal shipping restrictions by item category


**Item category:** Tetrahydrothiophene

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2412, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

> Tetrahydrothiophene 3 UN2412 II Prohibited 3A

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

Tetrahydrothiophene — Postal shipping restrictions by item category


**Item category:** Tetramethylammonium hydroxide, solid

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN3423, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Tetramethylammonium hydroxide, solid 8 UN3423 II 8A 8A

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

Tetramethylammonium hydroxide, solid — Postal shipping restrictions by item category


**Item category:** Tetramethylammonium hydroxide, solution

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 8, UN1835, packing group II; domestic mail air: 8A; domestic mail surface: 8A

> Tetramethylammonium hydroxide, solution 8 UN1835 II 8A 8A

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

Tetramethylammonium hydroxide, solution — Postal shipping restrictions by item category


**Item category:** Tetramethylene diperoxide dicarbamide

**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.

> Tetramethylene diperoxide dicarbamide Forbidden Prohibited Prohibited Prohibited Prohibited

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

Tetramethylene diperoxide dicarbamide — Postal shipping restrictions by item category


**Item category:** Tetramethylsilane

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 3, UN2749, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tetramethylsilane 3 UN2749 I Prohibited Prohibited

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

Tetramethylsilane — Postal shipping restrictions by item category


**Item category:** Tetranitro diglycerin

**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.

> Tetranitro diglycerin Forbidden Prohibited Prohibited Prohibited Prohibited

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

Tetranitro diglycerin — Postal shipping restrictions by item category


**Item category:** Tetranitroaniline

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.1D, UN0207, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tetranitroaniline 1.1D UN0207 II Prohibited Prohibited

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

Tetranitroaniline — Postal shipping restrictions by item category


**Item category:** Tetranitromethane

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 5.1, UN1510, packing group I; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tetranitromethane 5.1 UN1510 I Prohibited Prohibited

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

Tetranitromethane — Postal shipping restrictions by item category


**Item category:** Tetranitromethane

**Carrier:** USPS

**Restriction type:** prohibited

**Scope:** all mail

**Conditions:** Nonmailable Division 5.1 oxidizing substance

> Tetranitromethane.

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


**Item category:** Tetranitroresorcinol (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.

> Tetranitroresorcinol (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Tetranitroresorcinol (dry) — Postal shipping restrictions by item category


**Item category:** Tetrapropylorthotitanate

**Carrier:** USPS

**Restriction type:** restricted

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

**Conditions:** Hazard class 3, UN2413, packing group III; domestic mail air: Prohibited; domestic mail surface: 3A

> Tetrapropylorthotitanate 3 UN2413 III Prohibited 3A

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

Tetrapropylorthotitanate — Postal shipping restrictions by item category


**Item category:** Tetrazine (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.

> Tetrazine (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

Tetrazine (dry) — Postal shipping restrictions by item category


**Item category:** Tetrazol-1-acetic acid

**Carrier:** USPS

**Restriction type:** prohibited

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

**Conditions:** Hazard class 1.4C, UN0407, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited

> Tetrazol-1-acetic acid 1.4C UN0407 II Prohibited Prohibited

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

Tetrazol-1-acetic acid — Postal shipping restrictions by item category


**Item category:** Tetrazolyl 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.

> Tetrazolyl azide (dry) Forbidden Prohibited Prohibited Prohibited Prohibited

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

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