How email tracking works
Email open tracking can use a small remote image with a unique URL. When a mail client or its image proxy fetches that URL, the endpoint can record a signal; the network address, client details and timing available to it depend on the delivery path. Some senders also route links through tracking redirects. After you opt into a supported client, Mailshade uses Chrome's declarativeNetRequest to cancel receiver-side browser requests that match a reviewed tracker-pixel endpoint catalog 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 both mechanisms and their limits.
The tracking pixel
A small remote image can be embedded with a unique URL. A request for it can be interpreted as an open signal, although a mail provider may fetch or cache the image independently of the recipient opening the message. The image can be visually unobtrusive, while the request remains observable to the endpoint.
What a request can expose
- That the unique resource was requested, and how many requests were observed.
- A network address associated with the client or proxy, which may support approximate geolocation.
- Device or client details present in request metadata.
- The timestamp of each observed request.
Click tracking
Some links are rewritten to pass through an intermediary first. Contacting that redirect can create a click signal before forwarding to the destination. This is separate from the open-pixel mechanism.
How Mailshade handles it
declarativeNetRequest cancels receiver-side browser requests that match reviewed tracker-pixel endpoints. A cancelled tested request does not reach that endpoint from the page, but it does not establish every upstream or sender-side outcome; in Gmail, Google may have fetched or cached the image earlier. Mailshade locally detects supported click-tracking redirect patterns and, when a direct destination can be verified from the URL, lets you choose it or the 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 small remote image embedded with a unique URL. A client or proxy fetch can create a signal, and the network address, client details and time visible to the endpoint depend on the request path.
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 receiver-side browser requests matching reviewed tracker-pixel endpoints.
Can a sender track me without a pixel?
Pixel-based open tracking relies on an image request, while consent-based receipts and click redirects are separate mechanisms. Mailshade cancels matching receiver-side pixel requests and, for a supported redirect with a verified destination, lets you choose the direct URL or keep the original.
Does email tracking work if I never load images?
Pixel-based browser tracking needs the remote image request. Disabling remote images prevents those page requests but also removes ordinary images; it does not establish whether a provider fetched an image earlier. Mailshade instead targets reviewed tracker-pixel endpoints, allowing non-matching images 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.