(BTW, I can get addresses for people who are 2nd or 3rd cousins of mine I never met or knew existed till last few months, just using online searches and mostly free sites.)
Our building gets mail now and then for a relative of
occupants who left 2 plus years ago; the relative never
lived here, the occupants warned us “he is not welcome here”
Local PD visited once, asking about him. They were civil,
visit was in working hours.