# Open Tracking — PostFrame Tracking — EternalEngine

Invisible tracking pixels detect when recipients open your email. See open times, devices, email clients, and approximate locations.

[Back to Tracking](https://eternalengineos.io/features/postframe/tracking/)

Tracking

# Open Tracking

A one-pixel image at the end of the HTML records the first open, with the IP and user agent of the client that fetched it — and repeat opens inside the dedup window are ignored so one reader does not count twice.

[Start free](https://app.eternalengineos.io/signup?plan=free&interval=annual)[Tracking overview](https://eternalengineos.io/features/postframe/tracking/)

## Deep Open Intelligence

Invisible pixel tracking

1x1 transparent pixel injected automatically — recipients see nothing

Raw user agent

The client string is stored with the event, so you can tell Gmail from Apple Mail yourself

Deduplicated

Repeat opens within the dedup window are ignored; the email moves to opened once

Webhook on open

email.opened fires with the IP and user agent alongside the email's ID, subject and tags

Open Event Data

Open timestamp with timezone

Exact moment the recipient viewed your email

IP address

Recorded with the event

User agent string

The raw client string, for your own parsing

Email status: opened

The message moves from delivered to opened on the first pixel load

## Keep exploring PostFrame

[### Click tracking Signed redirects on every link. Open Click tracking →](https://eternalengineos.io/features/postframe/tracking/click-tracking/)[### email.opened webhook IP and user agent in the payload. Open email.opened webhook →](https://eternalengineos.io/features/postframe/webhooks/email-opened/)[### Dedicated analytics Engagement reports, per workspace. Open Dedicated analytics →](https://eternalengineos.io/features/postframe/multi-tenant/dedicated-analytics/)

Questions

## Common questions, straight answers.

How is an open detected?

A one-pixel image is appended to the HTML at send time. When the mail client loads it, PostFrame records the open with the IP and user agent of the request.

Why are opens sometimes lower or higher than expected?

Some clients block remote images, so those opens are never seen; others, such as Apple Mail with privacy protection, prefetch images and can register an open without a human reading. Treat opens as a signal, not a count of readers.

Does every open create an event?

No. Repeat opens inside the dedup window are ignored so one reader does not inflate the count; the email's status moves to opened on the first pixel load.

Is a pixel added to plain-text emails?

No. Open tracking needs HTML; plain-text messages carry no pixel and report no opens.

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