U.S. Customs and Border Protection (CBP) is responsible for inspecting all international mail arriving at U.S. airports, with limited exceptions. A major challenge for CBP is preventing imports of opioids and other illegal items mailed from overseas through the U.S. Postal Service (USPS). We conducted this audit to determine whether CBP's air mail inspection processes at JFK airport are effective and have adequate information technology (IT) security controls. CBP has ineffective processes and IT security controls to support air mail inspection operations at John F. Kennedy International Airport (JFK), the largest of nine USPS facilities that receive and handle incoming international mail. Despite legislative requirements to systematically target and widely prevent illegal imports, CBP inspects only a limited number of the hundreds of thousands of pieces of incoming air mail each day, largely due to difficulty inventorying and locating targeted mail, as well as having inadequate guidance, equipment, and resources. These air mail inspection deficiencies hinder CBP's efforts to prevent prohibited items (particularly opioids) from entering the United States.