11 Things Not to Send in the Mail

3. Fireworks

Fireworks and other explosives are a big no-no. “All fireworks, including sparklers and firecrackers, are prohibited from the mail because of the fire and injury risk if they’re mishandled in transit,” Ashley says.

4. Handguns

Mailing a handgun has been prohibited since 1927. Only licensed manufacturers, dealers and certain government agents can do it. Rifles and shotguns that are unloaded and properly packaged can be mailed to someone who is legally permitted to own them. The rules might soon change, however. In January 2026, the Department of Justice found the ban on mailing handguns unconstitutional, and the USPS has since proposed treating pistols and revolvers more like rifles and shotguns. As of Nov. 5, no final decision has been issued, so the 1927 rule is still in effect.

It’s important to note that even though you can ship certain firearms, USPS prohibits mailing ammunition. To send ammo, you must ship via UPS or FedEx Ground.

5. Cannabis and tobacco

Although many states have legalized marijuana for recreational and medicinal use, mailing it is still verboten, points out Ashley. You can, however, mail many hemp and CBD products — provided they don’t contain too much tetrahydrocannabinol (THC). “Hemp and CBD products are mailable if THC is 0.3 percent or below and the source is licensed,” she explains.

It’s not just cannabis: The Prevent All Cigarette Trafficking (PACT) Act — passed in 2010 to prevent the sale of tobacco products to minors — prohibits mailing cigarettes, “roll-your-own” tobacco materials, smokeless tobacco products like chewing tobacco, e-cigarettes and vapes. Cigars are not included in the PACT Act and are therefore mailable.

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6. Thermometers

Although modern thermometers are generally safe to ship, “older thermometers, blood pressure gauges and barometers containing liquid mercury can’t be mailed,” because they might break in transit, Ashley says. “A mercury spill releases toxic vapor, which is especially dangerous in an aircraft cargo hold.”

7. Lithium batteries

Because they’re combustible, lithium batteries — the kind used in electronic devices and portable chargers — are permissible only under certain circumstances, cautions Dmitrii Timin, owner of online shipping broker SMKlog. If the battery is inside a new phone, tablet or laptop, it can be shipped via the USPS without restriction, Timin says. Batteries that are inside used, damaged or defective electronic devices can be shipped only via ground transport and must be inside packaging marked “Restricted Electronic Device” and “Surface Transportation Only.”

“The rules for replacement batteries and portable chargers are stricter. They must be packed in their original packaging and have a capacity of up to 100 watt-hours,” Timin notes. “Damaged, defective or recalled batteries cannot be mailed.… These batteries pose a real fire risk.”

8. Animals

“The rules are stricter than most people realize,” Ewart says. “USPS only allows a narrow list of live animals, such as bees, day-old poultry, adult birds, scorpions and some small cold-blooded animals, and UPS and other private carriers are similarly restrictive.”

Even when an animal can legally be shipped, the trip can be dangerous. “Temperature, handling and access to food and water all affect whether an animal arrives safely,” Ewart continues. “If you need to move an animal, a specialized pet transport service is the [safest] route, as these providers are equipped to account for the animal’s welfare and specific travel needs.”

9. Perishable items

Perishable items include “fruits, vegetables, fresh meats and other articles that easily decompose or cannot reasonably be expected to reach their destination without spoiling,” Ewart says. They can also include things like flowers, plants and cakes, says Robert Carucci, the chief operating officer for the online gift seller Uncommon Goods.

If you’re shipping internationally, you should know that many perishable items are forbidden for agricultural reasons. “Mailing or shipping agricultural items from areas within the U.S. under federal or state quarantine for an invasive pest or disease can spread those threats, and various import restrictions also apply to most fresh fruits and vegetables depending on the country of origin,” Ewart explains. “Even if an item seems harmless, restrictions can vary significantly by country, and a package may be delayed, rejected or confiscated if it doesn’t meet the rules.”

Permissible perishable items are sent “at the mailer’s own risk,” the USPS notes. Heat is a major reason why. “Chocolate is the classic example: It’s shelf stable, but a few hours in a hot truck can leave it melted or discolored, so it often needs insulated packaging and cold packs in warmer months,” Carucci says.

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10. Health and wellness products

Because they’re highly regulated and potentially hazardous, what’s good for your health isn’t always good for the mail system. Take alcohol-based tinctures, for example, which the USPS won’t ship because they’re flammable, says Dave Wright, founder and CEO of the dietary supplement company Mind Lab Pro. “We tried shipping a vanilla tincture to a customer in Texas last year. The post office returned every package we sent, and we lost $400 in shipping fees plus two weeks of sales,” he says. “For those items, you must use UPS Ground or FedEx Ground with a flammable liquid label. You cannot put them on a plane, and you cannot drop them in a standard mailbox.”

Some products are allowed but ill-advised, such as probiotics. “That’s because they need cold temperatures to stay alive,” Wright explains. “USPS mail sits in hot trucks that reach 100 degrees in summer, and that heat kills the good bacteria. That is why we switched to overnight FedEx with ice packs for those orders.”

Heat can have the same degrading effects on medicine, so you should take the same precautions when mailing nonprescription drugs. Only licensed pharmacists and health care providers can ship prescription medication.

11. Money

While not illegal, sending money, checks or valuables is just too risky, experts say. “There are simply too many ways for it to go missing. And once it does, recovering it can be difficult,” Ewart says.

And what about Registered Mail? Nope, still not a great idea, says Ewart. Sending cash and other valuables isn’t advisable even by Registered Mail, which offers insurance of up to $50,000 — but only for eligible items. “USPS Registered Mail has specific exclusions for items such as cash, jewelry and precious metals, so consumers shouldn’t assume these valuables are automatically protected if something goes wrong,” Ewart continues.

Checks are risky, too. “Check washing — where thieves steal a check and alter the payee or amount — is a real and ongoing risk,” Ashley says. “Writing out the full amount, using permanent ink, dropping mail inside the post office rather than a collection box and signing up for Informed Delivery all help. Electronic payments remove the risk altogether.”