The Universal Postal Union (UPU) was founded in 1874 to harmonize the flow of postal services and unify its processes to constitute a single network with the UPU responsible for coordination and oversight. The UPU Joined the UN as a specialized organization in 1948, maintaining its headquarters in Bern, Switzerland. With 192 member countries, the UPU continues to support its members through a three-tiered network focusing on the Physical, Financial and Electronic aspects of the postal supply chain.
The safety of postal employees and customers is a critical element of managing the entire postal supply chain. That is why a number of goods and items are prohibited from travelling through the mail. UPU letter-post and parcel regulations clearly stipulate the type of items that cannot be sent by post internationally. Posts inform customers of these prohibited items, but the onus is on customers to certify that the packages and mail items they send through the mail do not contain items that could cause harm or danger to postal employees and customers.
More information on prohibited items may be found here: https://www.upu.int/en/Postal-Solutions/Programmes-Services/Postal-Supply-Chain/Customs#scroll-nav__3