The rules around international mailing of dangerous goods are a lot like being on a diet: There are a lot more things on the NOT ALLOWED list than on the allowable list. And even those few dangerous goods that are considered mailable have many restrictions on them. 

In international commerce, the term dangerous good is generally used to describe hazardous materials. Almost all hazardous materials are prohibited in international mail. The U.S. Postal Service’s International Mail Manual (IMM) and Publication 52 “Hazardous, Restricted, and Perishable Mail,” state the only mailable hazardous materials are certain infectious substances, excepted quantities of radioactive material, certain magnetized materials, and certain lithium and lithium-ion batteries. 

Postal officials recently updated a gathering of the International Mailers Advisory Group to educate international mailers and service providers on dangerous goods and on the recently created electronic mailbox that allows instant reporting of international incidents and steps for resolution.
“There has been an increased focus on dangerous goods in the mail,” said Mary Collins, Postal Service Global Trade Compliance - Operations Compliance Specialist. “Even though for years the USPS had a solid HazMat training program, in 2012 the ICAO (International Civil Aviation Organization) required each UPU (Universal Postal Union) Post member to be certified by their Civil Aviation Authority (CAA) as having met certain requirements in order to accept items containing lithium batteries. “

To satisfy these requirements, the Postal Service developed training modules and trained all postal employees based on their unique responsibilities. The training focuses on recognizing the potential dangerous goods in the mail, using updated acceptance procedures to prevent dangerous goods from entering the mail, and observing mail during handling for signs that pieces might contain dangerous goods. Along with the training, the Postal Service updated domestic mail procedures and developed materials specific for international mail. It enhanced online messaging to provide up-to-date information to customers, added a permissible dangerous goods check box in the customs declaration, and established a mechanism for incident reporting. This project was completed in coordination with the Federal Aviation Administration to limit the potential for non-mailable dangerous goods from entering the mail.

While lithium batteries have generated the lion’s share of recent attention, Collins noted that other dangerous goods also have many restrictions around them. Below is the list of some dangerous goods that are mailable internationally, with a summary of restrictions and/or pertinent rules. Explicit details and packaging requirements on these mailable dangerous goods can be found on

For a comprehensive list of mailable and prohibited hazardous material, visit Further, because individual countries have unique prohibitions and restrictions, mailers should always check the Individual Country Listings (ICL), found here.  

- Infectious substances: Biological substance, Category B, such as blood samples that may contain the flu virus. In general, to be mailable, these must come from a research lab or educational institution, with approval from manager of Product Classification (formerly Mailing Standards). 
o The outside of the package must be marked with proper shipping name (Biological Substance, Category B) and name and telephone number of person knowledgeable about material being shipped and emergency response requirements must be included. 
o UN3373 inside a diamond and orientation arrows. (See image) 
o Shipper’s declaration of dangerous goods.
o However, dry ice is non-mailable so infectious substances cannot be packaged in dry ice. 

- Radioactive Materials: They must have very low levels of radioactivity and both sender and recipient must have permission for the shipment.
o Must be sent by Registered Mail only.
o Both sender and recipient must have regulators’ permission, when necessary, from countries of origin and destination.
o Must comply with International Atomic Energy Agency Regulations

- Magnetized Materials: Magnetized materials that emit at distances greater than 7 feet are prohibited.
o No label required but if acceptance personnel see the Magnetized Material mark on the box, kit may indicate prohibited material. 

Lithium Batteries: Lithium batteries are considered by international authorities to be within the definition of “dangerous goods.” Items complying with the size and quantity restrictions (lithium batteries are limited to 4 cells or 2 batteries and no more than 2 laptops in a package) may be mailed internationally; however, packaging of the battery must comply with regulations that prohibit the use of the “Lithium Battery Handling” label or the “Class 9 Miscellaneous Dangerous Goods” label on the outside of the package for international mailing. 
o Batteries must be installed in the equipment they operate and protected from short circuit.
o No more than 2 batteries or 4 cells.
o Technical limits: non-rechargeable = 2 grams of lithium per battery; rechargeable = 100 watt-hours per battery.
o Equipment must have effective means of preventing it from being turned on or activated. 
o No labels may be present on the package.

Certain countries still prohibit the shipment of lithium metal or lithium-ion batteries into their countries, and lithium batteries are not allowed to be shipped to any country using Global Express Guaranteed service. As of today, the postal operators listed below have formally notified the Postal Service that they will not accept packages containing lithium metal or lithium-ion batteries: 
 Germany, Italy, Laos

This link will be updated accordingly if and when additional countries provide the Postal Service similar notification.  
Despite best efforts, at times, improperly or undeclared items get through, are identified by air carriers through their screening methods and are delayed or rejected. USPS currently handles these as dangerous goods incidents and is in the process of establishing and streamlining procedures for the return of mailpieces from air carriers and incident reporting relating to dangerous goods, prohibited items, inadmissible or wrongly admitted items in the mail. 

USPS’ Collins noted that improperly packaged lithium batteries and undeclared liquids and bottles account for a very high percentage of items rejected during screening. For both dangerous and non-dangerous goods, shippers are advised to adhere to the requirements of USPS Publication 52 and the ICL and to properly identify the package contents on customs forms to ensure that their shipments are not delayed or rejected by airlines or customs agencies. 

Shippers can also be proactive with customers by obtaining their advance authorization to resolve problems and by addressing mailability issues before shipping items that may be questionable in screening. Another action the mailer can take is to have mail service providers’ information on the custom’s form or package in the event there is a mailability determination to be made and the service provider has authority to act on the mailer’s behalf to resolve the issue. 
Kate Muth is the executive director of the International Mailers’ Advisory Group (IMAG). She produced the article in collaboration with the U.S. Postal Service to educate IMAG members on the mailability of dangerous goods. It is reproduced with permission. 

IMAG is the premier representative of the U.S. international mailing sector. Its core mission is to address barriers to the efficient flow of information and goods across borders. For more information on IMAG, contact Kate Muth at or visit the association’s website,