I hope they make it really strict. I'm sick of companies that send you spam ("newsletters") just because you interacted with them once, then when you unsubscribe, you get unsubscribed from that one list, so they keep spamming you just with a slightly different newsletter type. (Edit: Also, everything requiring a notification - by e-mail if they couldn't get me to install their app - just to get me to engage with their site.)
Once such behavior has the potential of landing your entire domain in the spam folder, maybe they'll be more careful.
Edit: For example, I can't imagine LinkedIn being able to pull of their "phish people, steal their address book, spam each contact three times with no opt-out" bullshit for so long if strict spam thresholds were in place.