An email tracking pixel is a remote image, usually one transparent pixel, embedded in an HTML message. When the image loads, your email client makes a request to the sender's server. That request tells the sender the message was opened.
The URL is unique to you
The pixel URL contains an identifier tied to your recipient record. The server does not need the visible email address in the request; the unique URL is enough to connect the open event to a campaign, recipient and message.
What the request can reveal
- Whether and when the message was opened.
- The IP address that requested the image, unless proxied.
- Approximate region inferred from that IP address.
- Email client and device hints from request headers.
- Repeated opens or forwarding, if the same pixel URL is requested from different networks.
Why blocking images works
If remote images are not fetched, the pixel cannot phone home. That is why many privacy-conscious clients block images by default, proxy images, or ask before loading external media. EmailGenerator.pro goes further for temporary inboxes: remote image sources are stripped before the message is stored, so the tracking request never fires from the message viewer.
Tradeoffs
Image blocking can make marketing emails look plain or incomplete. The tradeoff is usually worth it for verification mail, password resets and transactional notices, where the important information is text. For image-heavy newsletters you actually trust, a permanent inbox with per-sender image controls may be more comfortable.
What to read next
For a shorter definition, see what is a tracking pixel. For broader message safety, read email HTML security.