Perfume and cologne
Mostly ethanol, which is a flammable liquid at almost any retail concentration. Ships domestically ground-only under Limited Quantity; not mailable internationally at all.
International liquids
Can you ship liquid internationally?
An ordinary bottle of shampoo or a jar of honey, yes, once the destination country's own import rules clear it. A flammable liquid — perfume, nail polish, hand sanitizer, rubbing alcohol — no, not through the mail, and the reason is worth understanding rather than just accepting: the domestic exception that lets those goods travel on the ground evaporates entirely once the parcel is headed across a border. USPS Publication 52 chapter 6 spells out why, in wording read 2026-08-28.
USPS Pub 52 chapter 6, quotedDomestic exception, goneUS labels priced here
The border removes an exception
It does not add a rule so much as take one away. What survives the crossing is what was never conditional to begin with.
The domestic exception that does not travel
Domestically, a flammable liquid is not a flat no. USPS grades it on a flashpoint ladder, and most consumer flammables land somewhere in the middle of it rather than at the closed end.
| Flashpoint | Domestic mail position |
|---|---|
| 20°F (−7°C) or below | Not acceptable for mailing, at home or abroad |
| Above 20°F up to 73°F | Domestic surface transportation only |
| Above 73°F up to 100°F | Domestic surface transportation only |
| 100°F up to 140°F | Domestic surface only; may reclass as combustible |
| Over 140°F | Combustible liquid, air-eligible domestically as ID8000 |
That ladder, plus a second provision called Limited Quantity, is what lets a bottle of perfume or nail polish ride a UPS or USPS ground service today. Publication 52 section 621.3, read the same day, states the mechanism in one line: “The Limited Quantity category is unique within domestic commerce and is not recognized in international commerce.” Once that sentence applies, the flashpoint ladder above has nowhere to attach — there is no domestic-surface-only lane in international mail for it to sit in.
What replaces the ladder at the border
International mail runs on a much shorter list, and Publication 52 states it as a near-total ban rather than a graded scale. Section 621, read 2026-08-28: “In international commerce, hazardous materials are referred to as ‘dangerous goods.’ Almost all dangerous materials are prohibited in international mail. The only mailable dangerous materials are the following: 1. Certain infectious substances; 2. Excepted quantities of radioactive material that are allowed in domestic mail; 3. Certain magnetized materials; and 4. Certain lithium and lithium-ion batteries.”
Flammable liquids are not on that four-item list under any flashpoint. Section 623, read the same day, confirms it by hazard class rather than by degree: Class 3 flammable and combustible liquids and Class 8 corrosives are named among the classes barred from international mail outright, alongside the other seven hazard classes the section closes out. A liquid that clears the domestic ladder at, say, 90°F does not get a weaker version of that clearance overseas; it gets none.
Nail polish and remover
Solvent-based lacquer and acetone both carry a flashpoint well inside the flammable band. Same domestic-ground, no-international pattern.
Hand sanitizer and rubbing alcohol
High-proof ethanol or isopropanol. The concentration that makes it work as a sanitizer is the same property that puts it on the banned side of the border.
Liquids with no hazard class at all
None of the above touches a liquid that was never a dangerous good to begin with. Honey, maple syrup, olive oil, shampoo and most food or cosmetic liquids carry no hazard classification, so section 62's ban never reaches them — they are ordinary international mail, not an exception carved out of a prohibition.
That does not make them frictionless. The destination country's own customs and import rules still apply, in the same way our companion guide on food into Canada shows for a different product category: a declared value and description that match the contents, a commercial invoice on anything more than a personal gift, and whatever quantity or ingredient limits the receiving country sets for liquids specifically. Publication 52's own domestic containment standard — triple packaging with absorbent material for anything over 4 ounces — is not restated as an international-specific rule in chapter 6, but it remains the ordinary, sensible way to pack a bottle for a longer and rougher trip regardless of which rulebook is doing the citing.
UPS and FedEx do not reopen the door
USPS is one mail network among several, and the same shape of rule holds on the private carriers, even where the exact wording differs. UPS's own hazardous materials service definition page, read 2026-08-28, states that “UPS air service levels for export packages are UPS Express and UPS Expedited services,” and directs shippers with an origin or destination outside the US to a separate global dangerous goods guide rather than to the ground Limited Quantity path perfume and nail polish ride domestically.
The pattern across all three networks is the same: a domestic self-serve exception exists for consumer-sized flammable liquids, and it is scoped to the domestic network. An export shipment of the same bottle moves, if at all, through a contracted dangerous-goods program built around IATA air rules, not through the counter a private shipper uses for a birthday gift.
Where our checkout stops
SMKlog sells United States domestic parcel labels, and nothing that crosses a border, liquid or otherwise. A shampoo or honey shipment headed overseas is booked with the carrier directly, or routed to a freight forwarder's US address and priced here as the domestic leg. Anything on a pallet goes through freight review, where a person quotes the lane and, for dangerous goods, the paperwork it actually needs.
Where these rules come from
- USPS, Publication 52, section 621 — General Requirements (International Dangerous Goods) — the four-item mailable list and the Limited Quantity exclusion. Read 2026-08-28.
- USPS, Publication 52, section 623 — Nonmailable Dangerous Goods — Class 3 flammable/combustible liquids and Class 8 corrosives named among the barred hazard classes. Read 2026-08-28.
- USPS, Publication 52, section 343 — Flammable and Combustible Liquids — the domestic flashpoint ladder, Exhibit 343.21. Read 2026-08-28.
- UPS, Hazardous Materials Shipping Service Definition — export air service levels and the global dangerous goods referral. Read 2026-08-28.
Postal regulations, carrier dangerous-goods programs and every destination country's own import law are revised without notice. Treat the wording above as what these sources held on the date shown, and check the current text before shipping anything regulated across a border.
Common questions
Can you ship liquid internationally?
Ordinary non-hazardous liquids, generally yes, subject to the destination country's own rules. Flammable and combustible liquids, no: USPS Publication 52 section 623 lists Class 3 liquids among the hazard classes it bans from international mail outright, with none of the domestic flashpoint bands or ground-only carve-outs surviving the border.
Why does perfume ship domestically but not overseas?
Because the exception that lets it ship domestically does not exist internationally. Perfume, nail polish and hand sanitizer travel on USPS's or a carrier's Limited Quantity provision at home. Publication 52 section 621.3 states the Limited Quantity category is unique within domestic commerce and is not recognized in international commerce, so the provision that makes those goods mailable simply is not there once the mail is headed abroad.
What liquids are still mailable to another country?
Almost none that carry a hazard classification. Section 621 states that in international mail, the only mailable dangerous materials are certain infectious substances, excepted radioactive material already allowed domestically, certain magnetized materials, and certain lithium batteries — flammable liquids are not on that list under any circumstance. A liquid with no hazard classification at all, like honey, maple syrup or shampoo, is not covered by that ban and moves as ordinary international mail instead, subject to the destination country's own import rules.
Do UPS and FedEx handle this differently from USPS?
Not in the way that helps a private shipper. UPS's own hazardous materials service page states that export dangerous-goods packages ride only on UPS Express and UPS Expedited air service levels and points shippers to a separate global dangerous goods guide, rather than to the domestic Limited Quantity ground path perfume and similar goods use inside the US. The self-serve ground exception simply does not carry across a border on any of the three networks.
Can SMKlog quote an international liquid shipment?
No. Our checkout sells United States domestic parcel labels only. A liquid shipment leaving the country is booked with the carrier directly, routed through a freight forwarder's US address, which our calculator can price as a domestic leg, or handled through freight review when it is palletized.