We live in a world where data about what you do is very valuable, and people who want this data constantly look for ways to collect it. Your email is one valuable resource, and it’s possible your emails are embedded with a image that’s practically invisible and can be used to track you. This can be a message sent from a massive company, a tiny firm using a mailing list service to manage their transmissions, or an individual using mail software designed to embed a tracking email.
Tracking pixels embedded in emails allow a sender to know whenever the message is opened, track each date and time, and will alert them if the email was forwarded. The BBC reports that most emails now contain such trackers.