Unfortunate but this is a very common practice in the ad-tech world. Companies like LiveRamp rely on this "signed-up-email-sharing" between publishers to make t

Unfortunate but this is a very common practice in the ad-tech world. Companies like LiveRamp rely on this "signed-up-email-sharing" between publishers to make their email onboarding products (via which they are able to map email to cookie). Well, they claim to be privacy aware and won't let you map < 20 emails to cookie at a time but it's pretty easy to bypass that.