How do spammers know an email is active?

Question

I recently put my old Hotmail account on my phone, which I traditionally only checked a few times a year. I went from 1-2 spam emails every few months to several a day, after going through all the old ones and marking them as spam. How is this possible? I haven’t given this email out in years, and none of my monitoring services have flagged this email recently. It seems spammers somehow know this email is active again.

In: 146

Answer 1

Tracking pixel. It’s a small image inside the email that they send. When you open the email, you access the image, which pings their server. It’s basically a heartbeat that tells them that you open the email. Do not click on spam emails. Basically all of them use tracking pixels.