How email tracking works in Openn
Openn adds an invisible image and rewrites the links of each email you track from Gmail. When the image loads or a link is followed, Openn works out whether it was probably a person, an Apple preload, a security scan or you, and only counts the first.
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Step 01
When you send
The Openn Chrome extension adds a tracking switch to Gmail's compose window. Gmail's own Send button is unchanged. When you send a tracked email, the extension:
- adds a transparent 1×1 image to the end of the message, with a random identifier generated in your browser;
- replaces each link in the body with a link through Openn's redirect service, once the real destination has been recorded. Email addresses (
mailto:), phone numbers, in-page anchors, unsubscribe links and domains you have excluded are left as they are.
Sending never waits more than half a second for Openn. If our servers do not answer in time, the email leaves with its original links and only the image. The subject, the body and the list of recipients are not sent to Openn.
Step 02
What an “open” really is
No tracker sees a person read an email. What it sees is a request for the image. Several things can make that request:
Gmail
loads images through its own proxy, each time the message is displayed.
Apple Mail
with Mail Privacy Protection turned on, downloads images in advance on Apple's servers, whether or not the email is opened.
Corporate security filters
(Microsoft, Proofpoint, Mimecast, Barracuda and others) fetch images and links to inspect them before delivery.
You
when you look at your own sent email.
If images are turned off, nothing is requested at all. A tracker that counts every request adds all of these together.
Step 03
How each event is classified
For each request, Openn looks at a few traits: the kind of mail client, the kind of network it came from, and the time since the email was sent. It keeps the resulting class and discards the raw IP address and User-Agent.
You.
When you display one of your tracked emails in Gmail, the extension tells Openn. Loads through Gmail within 15 seconds of that are yours. A load through Gmail's proxy within 3 seconds of sending is also yours: it is Gmail showing you the message you just sent.
Apple preload.
A request from Apple's network with the generic identity Apple's proxy uses.
Security scan.
A known robot, a request from an email security vendor's network, or a request from Microsoft's network less than 30 seconds after sending.
A person.
Everything else.
Your own views and security scans are never counted. The rules are tested against real opens collected from real mail clients.
Step 04
What you see
When you open one of your sent emails in Gmail, a line above the message gives the result in one of these forms:
| Result | What it means |
|---|---|
| Reliable | Opened N times. Every open came through Gmail's image proxy, which fetches the image again each time the message is displayed, so the count follows actual views. |
| Estimate (at least N) | At least one open came from a mail app that keeps the image after the first load. Later views never reach us, so the number is a minimum, not a total. |
| Apple preloaded | The only signal is Apple fetching the image in advance. It is shown as a single, unconfirmed signal and says nothing about whether anyone read the email. |
| Security scan | Only a security filter touched the email. It is not counted as an open. |
| Not opened yet | No signal from a person so far. This is not proof that the email is unread: the recipient may have images turned off. |
For an email with several recipients, the result starts with Global tracking and the number of recipients: at least one of them opened it. Openn does not know which one.
On the Pro plan, Chrome can also notify you when a person opens an email or clicks a link. Notifications are off until you turn them on, work while a Gmail tab is open, and include neither the subject nor the recipients.
Step 05
Clicks
A tracked link goes to Openn's redirect service, which records the click and sends the recipient on to the destination recorded when you sent the email. It cannot send anyone elsewhere. Clicks go through the same classification: a security filter following links is not counted. A click can be recorded even when images are turned off.
Under the result line, each link shows its own clicks and when the last one happened.
Step 06
What Openn cannot know
- Whether the email was actually read, or for how long.
- Which recipient opened an email sent to several people.
- Anything, when the recipient's mail app does not load images.
- Your own views from a device where the extension is not running, such as the Gmail app on your phone: they look like a recipient's and are counted.
This is why every result carries its label. What Openn stores along the way is described on the security page.
Send the email.
Know what happened next.
Useful email signals, without the surveillance theatre.
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