I use GMail. I'm sure they are aware that I mark anything that's not personal as "spam" and never even open it. I can count on one hand how much spam I get every 2 years. I also use a robust ad blocker and block 3rd. party cooties..

These types of emails – from businesses offering products and services – can be monitored by the sender, whether you knowingly signed up or not. Data sent back to email marketers includes whether you’ve opened the email, how long for, and which links you’ve clicked on.