I was encouraged to join F/B & after a while I read an article which pointed out that it was possible for my E/M address to be accessed from anywhere in the world,& after I had received a few dodgy E/Ms I decided to drop out sharpishly ( I fortunately no longer subscribe to F/B).
I had a email the other day which looked like an FB email, but took me to an advert. I'm deleting any emails I get from FB these days, if I want to look at the site I go straight there instead.