Chicago — A US Postal Service mail carrier was robbed by two men in Logan Square on Friday evening, the latest crime in an ongoing assault on the mail system in Chicago. “Never put anything into the postal system unless you are comfortable with it landing in the hands of criminals instead of at its intended destination,” advised an investigative source. Like dozens of other mail carriers, the postal worker robbed on Friday was targeted for her “arrow key,” a US Postal Service universal master key that opens collection boxes, parcel lockers, mailbox panels, and apartment building mailroom boxes. The...