From the Objective: "Our objective was to evaluate the U.S. Postal Service's preparedness for processing international election mail, including military and diplomatic mail. The Postal Service processes international election and political mail for eligible U.S. citizens throughout the world. Military and diplomatic members and their families or other U.S. citizens located in foreign countries can use or receive these types of mail. Election mail is any item mailed to, or from, authorized election officials that enables citizens to participate in the voting process. For example, local election offices in the U.S. send ballots or other election materials to international recipients and the international voters mail their completed election ballots back. Political mail is related campaign or messaging mail, and generally entails only outbound operations. International election and political mail are typically processed at one of the five International Service Centers (ISC) which are located in New York, Miami, Chicago, San Francisco, or Los Angeles. Processing operations for military and diplomatic election mail are co-located with Postal Service processing functions for other international mail (i.e., letters, parcels, periodicals, etc.). Most international military and diplomatic mail is processed through the Chicago facility, and it is estimated this facility will receive about 80 percent of inbound military mail ballots for the 2020 presidential election. International political and election mail has distinct processing procedures."
U.S. Postal Service, Office of Inspector General, Report No. 20-271-R20