See mailshade.org

How to tell if an email is being tracked

An email can include a small remote image with a unique URL. A fetch by the mail client or its image proxy can create a signal, and the metadata available to the endpoint depends on that delivery path. The image can be visually unobtrusive, so reading the message alone does not establish whether it contains a tracker. Mailshade's DOM scan detects suspicious pixels and supported tracking-link patterns in opened messages, while declarativeNetRequest independently cancels receiver-side browser requests that match a reviewed tracker-pixel endpoint catalog. A red-eye overlay names what the local scan detected across Gmail, Outlook, Office 365, Superhuman, Yahoo Mail and ProtonMail. The dashboard records detections; DNR cancellation is separate network evidence. In Gmail, a receiver-side cancellation does not establish whether Google fetched or cached the image earlier.

Signals worth checking

  • The message contains a small or visually hidden remote image.
  • An image or link uses an unfamiliar endpoint or an opaque redirect path.
  • A tracker-detection tool flags a pixel or supported tracking-link pattern on the opened message.

How to check a specific message

  1. Install Mailshade, opt into your mail client, and open the email.
  2. Look for the red-eye overlay on an opened message with a detected tracker.
  3. Read the reported tracker origin to see what the local scan matched.
  4. Open the dashboard to see that sender's detection history.

From detection to blocking evidence

Mailshade separately uses DNR to cancel receiver-side browser requests matching reviewed tracker-pixel endpoints. A heuristic pixel or link detection is useful evidence, but is not itself proof that every associated request was network-blocked.

Why some emails show nothing

An absence of the red eye means the local scan found no matching signal; it is not a guarantee that no unknown or unsupported technique exists.

FAQ

Can I tell an email is tracked just by reading it?

Not reliably. A tracking image can be visually unobtrusive. A tool such as Mailshade can identify signals that match its local detection logic, but an absence of a match is not proof that no unsupported technique exists.

Does the red-eye overlay work outside Gmail?

Yes. In each opted-in integration, Mailshade can show an opened-message detection and, where the webmail exposes stable identity, mark the matching inbox row. It reports the tracker origin matched by the local scan.

Does detecting a tracker also block it?

Mailshade uses declarativeNetRequest to cancel receiver-side browser requests matching its reviewed tracker-pixel endpoint catalog. Its DOM scan can also detect heuristic pixels and supported tracking links, so a dashboard detection is not by itself proof that every associated request was blocked.

Will checking for trackers send my email anywhere?

Detection runs locally, and core inbox history is not sent to Mailshade servers. Tracker events stay in IndexedDB with URLs reduced to origins; settings can use Chrome Sync. Paid auth/Polar calls and optional off-by-default privacy-filtered Hawk crash reports are separate.

Is Mailshade free to check my email for trackers?

Yes. Core blocking, inbox detection, link warnings, rolling seven-day history and a top-10 sender view remain free after a 14-day Pro trial. Paid Pro adds full history, top 30 and CSV export.