<img src="https://track.example.com/o/8f3a2c.gif" width="1" height="1" alt="">
Each pixel URL is unique to one recipient and one message, so the tracking server knows who opened what. Click tracking works the same way with links: each link is rewritten to pass through a tracking domain first.
Why open rates are unreliable
- Apple Mail Privacy Protection, on by default for many Apple Mail users since 2021, loads images in advance, so emails can count as opened when nobody read them.
- Some corporate security gateways open links and images to scan them, which adds false opens and clicks.
- Mail apps that block images by default hide real opens.
Open tracking and cold email
To track opens, the email must be HTML, and a pixel from a shared tracking domain is one more thing filters can judge. Plain text emails look like a person wrote them, and for cold email they often land better. That is why many teams switch open tracking off and measure reply rate instead. If you do track, use a custom tracking domain rather than a shared one.
In ZicReach, new campaigns are text only by default, because plain mail lands in the inbox more often. Open and click tracking need HTML, so turning tracking on switches text only off; you choose per campaign, and a custom tracking domain is available when tracking is on. See the settings on the AI Email Marketing page, and test your subject line with the subject line tester.