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Deliverability Letter

Spy Pixel

Also known as: Tracking Pixel, Tracking Bug

A spy pixel is a tiny invisible image in an email that tracks when someone opens it. It helps email marketers measure open rates in a simple way.

Spy pixels are tiny invisible images hidden inside emails. When someone opens the email, their email client loads the image from a server. That load tells the sender that the email was opened. It feels like a quiet read receipt that sits in the background.

Email marketers use spy pixels to see if subject lines work and if emails reach the inbox instead of spam. The data shows how many people opened, roughly where they are, and what device they used. This helps teams improve send times, content, and list quality. It is basic analytics, not secret spying.

If you send marketing emails, treat spy pixel data as a rough guide, not a perfect truth. Image blocking, privacy tools, and mail features can inflate or hide opens. Look at trends over time instead of single numbers. If you are a subscriber, you can block remote images if you want more privacy.