Postal censorship - Definition from the Hotspot Shield Encyclopedia
This is a form of governmental censorship where public mail is examined and sometimes altered or destroyed depending on its contents.
Mail can be used to spread dangerous ideas with little tractability and especially in times of war or concerning criminal organizations, mail could be an area of communication that needs to be monitored. Postal censorship could involve opening and examining of mail at mail distribution centers before it is forwarded on to the intended recipient. Depending on the content and if it is deemed threatening or offensive, it may be completely obliterated and prevented from being sent on to the recipient. The sender may never know that their mail has been destroyed or examined. Usually postal censorship is linked to espionage and times of war.