Tracking pixels in pages and email
Why it matters Many marketing emails and web pages contain an image you cannot see. When it loads, the sender learns that you opened the message, when, and roughly where. A single setting in your mail app can stop most of this.
The invisible postcard
Imagine a letter with a tiny stamped postcard glued inside, already addressed back to the sender. The moment you open the letter, the postcard posts itself. The sender learns you opened it, and the postmark shows when and from which town. A tracking pixel is that postcard.
Tracking pixel (also called a web beacon): a tiny image, often 1 by 1 pixel and transparent, whose only job is to be downloaded. Downloading it sends a request to the tracker's server, and that request is the report.
How it works
To show an image, your device must ask a server for it. Each request includes your IP address (which hints at your rough location and network), the time, and some details about your device. The pixel's web address usually also carries a code unique to you:
https://mail.adco.example/open.gif?campaign=spring&r=8f31c2Here r=8f31c2 stands for one recipient. When that address is requested, the sender's records say "recipient 8f31c2 opened the spring email at 08:14 from a phone".
Web pages use the same trick. A page can load a pixel from adco.example to report "this visitor saw the checkout page". Pages can also send these reports without any image at all, using a browser feature built for sending small reports as a page closes. Either way, it is a beacon: a small message home.
Open tracking: counting who opened an email, and when, by noticing which pixels were downloaded. "Read receipts" in some marketing tools are built this way, without asking the reader.
Apple Mail Privacy Protection
In 2021 Apple added Mail Privacy Protection to its Mail app (checked October 2026). When it is on, Mail downloads remote images in the background through relay servers, usually when the email arrives, whether or not you open it. The sender sees a relay's address instead of yours, and an "open" that may not be a real open.
This makes open tracking unreliable for those readers. Other mail services also fetch images through their own servers, which hides your IP address, but the timing of the download can still reveal when you opened the message.
What you can do
- In your mail app, look for a setting such as "Load remote images" or "Show external content" and turn it off, or set it to "Ask". You can still click to show images in mail you trust.
- On Apple devices, the setting is called "Protect Mail Activity" in Mail's privacy settings (checked October 2026).
- Remember that links in emails are often tracked too: they pass through the sender's server before reaching the real page.
A common misconception
"If I do not see any pictures, there is no pixel." The pixel is designed to be invisible. A plain-looking text email can still contain one. Blocking remote images is the reliable way to stop it.
Recap
- A tracking pixel is an invisible image whose download is the report.
- The request reveals the time, your IP address (rough place) and a code for you.
- Mail Privacy Protection and image proxies make opens unreliable and hide your IP (checked October 2026).
- Turning off remote images in your mail app stops most email pixels.
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