"[Email tracking] tech is pretty simple. Tracking clients embed a line of code in the body of an email—usually in a 1x1 pixel image, so tiny it's invisible, but also in elements like hyperlinks and custom fonts. When a recipient opens the email, the tracking client recognizes that pixel has been downloaded, as well as … Continue reading You Give Up a Lot of Privacy Just Opening Emails. Here’s How to Stop It | WIRED