Tracking is everywhere on the Internet. Over the past year, a drumbeat of tech-industry scandals has acclimated users to the sheer number of ways that personal information can be collected and leaked. As a result, it might not come as a surprise to learn that emails, too, can be vectors for tracking. Email senders can monitor who opens which emails, when, and what device they use to do it. If you work for a business or a non-profit that sends mass emails, maybe you’ve used tools to perform this kind of tracking before. Even if you have used them, this might be the first you’ve heard of it — because unfortunately, in email marketing software, tracking is often enabled by default.