Is this throught the post office?
There was a one-season reality show, “Hunted,” where 2-person teams of ordinary folks tried to outsmart the FBI, US Marshalls, etc., and not be found for several weeks. I think there were 9 teams and 2 made it through to the end. Law enforcement got on the trail of one team through the mail. The show showed how mail is scanned. LE asked for a list of the mail being sent by family and friends and in checking out those addresses was able to find a location where one of the teams had been hiding, but that team had already moved to a new location. It was very interesting seeing the various methods LE used, and seeing how people’s habits (like a love of Taco Bell) would be what led to their being found.