How to tell if an email is being tracked
An email is tracked when it carries a 1x1 pixel image whose load reports back to the sender the moment you open the message — your IP, device and the open time. The hard part is that the pixel is invisible, so you cannot tell by reading the message. The practical way to know is a tool that inspects incoming mail for known tracker domains and surfaces them. Mailshade shows a red-eye overlay on any flagged message and names the tracker domain it found, so you can see at a glance whether a given email is watching you. It does this across Gmail, Outlook, Office 365, Superhuman, Yahoo Mail and ProtonMail. The same extension then blocks the pixel request via declarativeNetRequest, so identifying a tracker and stopping it happen in one step rather than two.
Signs an email is tracked
- It comes from a marketing, sales, recruiting or newsletter sender.
- It contains remote images that load from a domain you do not recognise.
- A tracker-detection tool flags a known pixel domain on the message.
How to check a specific message
- Install Mailshade and open the email in your client.
- Look for the red-eye overlay — it appears only on messages with a detected tracker.
- Read the tracker domain it reports to confirm what was found.
- Open the dashboard to see whether that sender has tracked you before.
From knowing to blocking
Detection alone does not protect you — a warning-only tool lets the pixel fire anyway. Mailshade cancels the request at the network layer via DNR, so once it has identified the tracker, the open signal is never sent.
Why some emails show nothing
Plain personal email and most transactional receipts carry no tracker, so they show no overlay. An absence of the red eye is itself useful information.
FAQ
Can I tell an email is tracked just by reading it?
No. The tracking pixel is a 1x1 transparent image, invisible in the message body. You need a tool that detects known tracker domains, such as Mailshade's red-eye overlay, to know for certain.
Does the red-eye overlay work outside Gmail?
Yes. Mailshade flags tracked messages across Gmail, Outlook, Office 365, Superhuman, Yahoo Mail and ProtonMail, naming the tracker domain it detected on each.
Does detecting a tracker also block it?
With Mailshade, yes. The same extension that flags the tracker cancels its pixel request via declarativeNetRequest, so detection and blocking happen together rather than requiring a second tool.
Will checking for trackers send my email anywhere?
No. Detection runs locally in the browser. Blocked events stay in IndexedDB on your device, with no analytics and no servers handling your inbox.
Is Mailshade free to check my email for trackers?
Mailshade is paid, from $3.99 per month or $19 one-time for Founders Lifetime. Its source is open under AGPL-3.0, so you can audit the detection logic before paying.