Email tracking, from the recipient's chair

Before you install anything that tells you when your email has been read, you want an answer to one question: can the person receiving it tell? Search for it and you will find a run of confident denials, most of them published by companies that sell email trackers, and almost none of them carrying a citation to anything.

There is a better way to settle it. Stop reading sender-side marketing and go sit in the recipient's chair. What does an ordinary inbox, on its default settings, actually show the person at the other end? Microsoft, Google, Proton and DuckDuckGo all answer that in their own documentation, and the answer turns out to point at the way you should be sending anyway.

Outlook blocks the pixel by default, and says why

Start with the most widely deployed business mail client. Microsoft states that classic Outlook is configured by default to block automatic picture downloads from the Internet, and among the advantages it lists is this one: “Helping you avoid tracking pixels: invisible images that can tell a sender you've read the email.” Microsoft then adds a parenthesis of its own, “Note: tracking pixels aren't the same as a read receipt.”

Two things follow. The first is that Microsoft names the mechanism in a mainstream help article rather than treating it as an obscure detail. The second is what the reader sees: a bar at the top of the message offering Download Pictures, which is a prompt about your email specifically, appearing before they have decided anything about you.

Gmail shows the images, until it decides not to

Gmail behaves differently. Google says that by default, when you get an email with an image, you will see the image automatically, and the same page offers an “Ask before displaying external images” setting for anyone who wants the Outlook behaviour instead. In that mode, Google writes, “When you get a message with images, see the images by clicking Display images below.”

The line worth reading twice is the one Google attaches as a note: “If Gmail thinks a sender or message is suspicious, you won't see images automatically. Instead, you'll be asked if you want to see the image.” Gmail scans every message for suspicious content, and a new address writing to somebody who has never replied to them sits close to that description. The image prompt is not only a setting a privacy-minded reader turned on. It is also something Gmail can decide about you.

Two mailboxes hand the reader a list

The clearest tells are not prompts at all. They are reports. Proton Mail says its Block email tracking feature is enabled by default, and describes what the recipient gets: “When Proton Mail detects trackers in an email, you'll see a tracker protection badge at the top of the message. The badge tells you how many trackers were blocked and how many links were cleaned.” On the web app it also strips known tracking parameters out of the links you sent.

DuckDuckGo goes one step further. Its Email Protection service forwards mail to a normal Gmail or Outlook inbox with trackers removed, and in the announcement opening the beta to everyone in August 2022 the company described a Personal Duck Address this way: “Within forwarded emails, we'll tell you how many trackers we've removed, what company appears to be behind them, and other helpful information.” In the same post DuckDuckGo reported that roughly 85 percent of its closed beta testers' emails contained hidden trackers.

The free tier that signs its own work

The oldest tell in this category is the one the tracker prints itself. Mailsuite, formerly Mailtrack, documents it plainly: “Upon signing up, Mailsuite adds a branded signature, ‘Sent with Mailsuite,’ which includes an unsubscribe link, to every new email you compose.” The same page says you can remove it permanently or just for the message in front of you, which is more generous than the common claim that free trackers advertise themselves forever.

Ours does the same thing, so it belongs in this list rather than in a footnote. The Fast Mail Tracker free plan carries a small “Sent with Fast Mail Tracker” line on the messages you send, and the paid plan removes it. We would rather you read that here than discover it in somebody's reply.

The link that does not go where it says

Click tracking has no invisible version. Measuring a click means rewriting the destination so it passes through the tracker's domain first, which is why a tracked link shows an unfamiliar host in the browser status bar when the reader hovers over it, and why the address they land on is often longer than the one you thought you sent. Every vendor that offers click tracking does this, including us.

Both privacy mailboxes above treat those rewritten links as something to report. Proton counts cleaned links on its badge. DuckDuckGo added Link Tracking Protection for the same reason. A reader does not need to understand redirects to notice that the badge says two trackers and one link.

Show original, and the people who automate it

Anyone can open Show original in Gmail and read the raw message, pixel and all. Almost nobody does, and articles that rest the whole answer on that fact are technically right and practically useless. What changed is that the reading got automated. Ugly Email is an MIT licensed extension that, in its own description, “scans through your inbox and looks for emails containing tracking pixels. Tracked emails are labeled with an eyeball icon, and the tracking pixel is blocked.” Detection runs locally in the browser, and the site publishes the list of trackers it recognises.

Keep the scale honest: its Firefox listing reports daily users in the low thousands, so this is a minority habit rather than a wave. The minority skews technical, and technical buyers are often the exact people a founder most wants to reach.

Microsoft, Google, Proton, DuckDuckGo and the tracker vendors themselves all document this in public. The recipient does not have to be an expert. They have to read their own inbox.

How to send so the answer stops mattering

Treat detectability as a design constraint rather than a risk to manage, and the sending gets better on its own terms.

• Rank the signals that survive scrutiny. A click and a reply are things a person decided to do, and Apple notes that Mail Privacy Protection does not extend to links or email attachments. An open can be recorded by a proxy that no human was sitting behind.
• Be able to say it out loud. “I use a tool that tells me when my email has been opened” is an ordinary sentence now. If saying it to the recipient would embarrass you, the thing to fix is the message, not the tracker.
• Read the vendor's own compliance line. Mailsuite closes its signature help page with “Please, ensure you comply with the applicable data protection regulations.” The vendor is telling you whose duty it is.
• Track people you had a reason to write to. A tracked message somebody was expecting is unremarkable. The same pixel on a cold blast to a scraped list is the case the detector extensions were built for.
• Keep your own numbers honest, because a dashboard that counts proxy fetches as reads will send you chasing people who never looked.

That last point is where Fast Mail Tracker takes a firm line. Apple Mail privacy opens and other proxy fetches are rejected outright rather than counted, so an open in your timeline is attributed to a real recipient, with clicks and any reply sitting beside it on the same thread.

Fast Mail Tracker is in early access while we work through Google's security review, so places are limited. If you would rather send email you could explain to the person receiving it, install it from the button below.