Maybe it's just me, but I think I hate those things more than anything else on the current web. Maybe even more than autoplay videos.
Of the people who see the pop up, the conversion rate is highest for those who see it immediately. And there's not a significant effect on bounce rates.
I have no idea why! I would never simply give my email address to an immediate pop up modal.
We are power users, a lot of people have no idea what they're doing on the web.
Edit: I am new to HN, why this was downvoted?
(why are you being downvoted? No idea, you make a reasonable, articulate statement, with a credible explanation. Sometimes it just happens on HN. I like to assume people are accidentally clicking the [▼] character by mistake).