Open Pixel
A tiny invisible image embedded in emails that loads when opened, tracking when recipients view the email.
Definition
An open pixel (also called tracking pixel or beacon) is a tiny, invisible image (typically 1x1 pixel) embedded in HTML emails. When the recipient opens the email and images load, the pixel is requested from the tracking server, which records the open. This is the primary method for tracking email open rates, though it has significant limitations.
Why It Matters
Open tracking provides valuable engagement data - who opened your email and when. This data informs segmentation, automation triggers, and campaign optimization. However, pixel tracking has significant limitations: image blocking prevents tracking, and Apple's Mail Privacy Protection pre-fetches pixels, inflating open rates.
How It Works
A unique image URL is generated for each recipient and embedded in the email HTML. When the email is opened with images enabled, the browser requests the image from the tracking server. The server logs the request (including who, when, and sometimes location) and returns a tiny transparent image.
Best Practices
- 1Use open tracking as one signal, not the only metric
- 2Do not rely solely on opens for automation triggers
- 3Consider click tracking as a more reliable engagement signal
- 4Account for MPP and image blocking in your analysis
- 5Complement pixel tracking with other engagement indicators