The United States Postal Service handles an enormous volume of mail every day, moving millions of packages quickly and efficiently across the country. Most of the time, it’s easy to assume you can send just about anything as long as it fits in a box. But that’s not always the case.

Certain everyday items can pose safety risks, violate mailing rules, or simply increase the likelihood of your package being lost or stolen. Some are clearly dangerous, while others seem harmless until you look a little closer. In many cases, the issue comes down to theft, damage, or strict shipping restrictions.

Even well-intentioned packages can cause problems if you don’t know the guidelines. Taking a few extra minutes to understand what not to mail can save you time, money, and frustration. Here are some everyday items you should think twice about before sending them through the mail.

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Cash and Gift Cards

Sending cash or gift cards through the mail is one of the easiest ways to lose money without any way to recover it. If the envelope is stolen, there’s little chance of tracking or replacing its contents.

Checks

Mailing checks might feel routine, but it’s become increasingly risky due to rising mail theft and fraud. Criminals can alter stolen checks and redirect the money, making it safer to use electronic payment methods whenever possible.

Ammunition

Ammunition is considered hazardous and is strictly prohibited from being sent through the mail. It poses serious safety risks during transport and can result in legal consequences if mailed.

Alcohol

It may seem like a thoughtful gift, but alcohol cannot be mailed through USPS unless you are a licensed shipper. Anything with more than 0.5% alcohol content is considered nonmailable under postal regulations.

Pets

Sending pets through the mail is not allowed for most animals, including common household pets like cats and dogs. These animals require care during transit, making standard mailing both unsafe and prohibited.

Marijuana

Even if marijuana is legal in your state, it cannot be sent through the mail under federal law. The only exception is hemp products that meet strict THC limits.

Fireworks

Fireworks are classified as hazardous materials and are completely banned from mailing due to the risk of explosion. Even small items can pose serious danger during handling and transport.

Traditional Thermometers

Old-style thermometers often contain mercury, which is toxic and dangerous if released. Because of the risk of breakage and exposure, these items are not allowed in the mail.

Perfume

Perfume often contains alcohol, which makes it subject to restrictions and eligible only for certain types of ground shipping. Improper packaging or labeling can result in delays or penalties.

Nail Polish

Nail polish is considered flammable due to its chemical composition, so it cannot be shipped without meeting strict shipping guidelines. Many standard mail services won’t accept it without proper handling.

Hand Sanitizer

Most hand sanitizers contain alcohol and are treated as hazardous materials. They can only be shipped under specific conditions, usually limited to ground transport with proper labeling.

Items Containing Mercury

Items like barometers and certain medical devices may contain mercury, which is highly toxic if released. Because of the potential health risks, these items are prohibited from being mailed.