How email tracking works
Email tracking works by hiding a 1x1 transparent image inside a message. Its unique URL reports the open, IP, device and time when fetched. Some senders also route links through tracking redirects. After you opt into a supported client, Mailshade uses Chrome's declarativeNetRequest to cancel requests to known tracker-pixel domains across Gmail, Outlook, Office 365, Superhuman, Yahoo Mail and ProtonMail. Its local DOM scan separately detects pixels and supported tracking-link patterns. This page explains how both signals work.
The tracking pixel
A 1x1 image is embedded with a unique URL. Loading it is the open event. Because it is one transparent pixel, you never see it, but the request to the sender's server is what leaks the open.
What the sender learns
- That the email was opened, and how many times.
- Your IP address — and from it, approximate location.
- Your device and email client, from the user-agent.
- The exact timestamp of each open.
Click tracking
Links are often rewritten to pass through the sender's server first. The redirect logs the click and which link, then forwards you on. This is separate from the open pixel.
How Mailshade handles it
declarativeNetRequest cancels requests to known tracker-pixel domains before they leave the browser. With no request, there is no open event from that domain. Mailshade locally detects known click-tracking redirect patterns and lets you choose the direct destination or original tracked URL; the dashboard records detections rather than claiming every detected signal was blocked.
FAQ
What is a tracking pixel?
A tracking pixel is a 1x1 transparent image embedded in an email with a unique URL. When your client loads it, the request tells the sender you opened the message, along with your IP, device and the time.
What is declarativeNetRequest?
It is the Chrome MV3 API that lets an extension declare rules to block or modify network requests. Mailshade uses it to cancel requests to known tracker domains before they fire, which is how it blocks the open pixel.
Can a sender track me without a pixel?
Open-tracking relies on the pixel request, so blocking a known tracker-domain request stops that open signal. For a locally recognized tracking redirect, Mailshade lets you choose the direct destination to avoid it or keep the original URL.
Does email tracking work if I never load images?
Open-tracking needs the image to load, so disabling all remote images stops it but also removes ordinary images. Mailshade instead blocks known tracker domains, allowing images from other domains to continue loading.
Is there a free way to block tracking pixels?
Yes. Mailshade keeps core protection free after a 14-day Pro trial, with rolling seven-day history and a top-10 sender view. Paid Pro starts at $3.99 per month or $19 one-time; its source is open under AGPL-3.0.