My old aunt Lil had numerous siblings with whom she'd lost touch over the years, particularly her brother Leslie. She'd been told he'd died of cancer many years before. Imagine her shock when decades later the phone rang and a voice piped up, "It's your brother Les!" She was disgusted that anyone could play such a cruel joke and hung up. It rang again and eventually the man persuaded her he was indeed my uncle Les, alive and well. They were reunited after all those years.
As for me, I'd never open an email from an unrecognised or suspect source. If folk want to get in touch that badly, they can jolly well do so by post! Same goes for unsolicited phone calls. I tell them to write if they need to contact me. They ought to have my address if they're legit.