Years and years ago, my grandmother kept getting mail for my grandfather from a certain magazine/book/'win the sweepstake' company. Grandfather had been dead for 30+ years at the time. No matter how many times GM returned them with 'return to sender - recipient deceased' on the envelope, they kept sending them.
Eventually she sent them an envelope back with 'please redirect to Upper Outer WoopWoop Cemetery'. The mailings stopped.