It gets quite fun if you don't use it. Facebook starts sending really needy notifications like "X just commented on a picture" or "Y just liked this" to try and make you login. I think there's an apocryphal metric (which is probably true) that users must always have one unread notification when they login. There's no way of turning these messages off short of unfollowing every one of your friends individually.

Yeah if I haven't logged in in a bit but there aren't any "real" notifications, it gives me a notification like "Do you know N", where N is invariably a person I've never met, with whom I have no mutual friends or common groups.

Interesting. My FB account is dormant but not deleted. I have not used it in over 5 years, and I don’t recall seeing emails like this.

They probably give up at some point, and may have built the feature less than 5 years ago.

I only get this on mobile (having the app installed), email is thankfully unaffected. But presumably if you logged in, you'd find a bunch of notifications that were largely irrelevant to you.

I have noticed that if you have the app open but have no activity for a short while they pop up a notification, often for something relatively obscure like a new comment in a group that you're a member of, I guess to try and regain your interest. I definitely fell for it the first few times.

Hmmm, I think LinkedIn does this as well... I've seen it more than a couple times now and I hate seeing badges on any of my mobile apps.