Marketing Calendar 2026
Confirmed Open Rate (COR)
Confirmed Open Rate (COR) is a metric used in email marketing to measure the number of recipients who opened an email. As the standard ’email open’ tracks every open event, COR counts only those opens you can be sure about.
Most email platforms track “opens” by placing a tiny invisible image (a tracking pixel) inside. This image sends an event to the system saying that the email has been opened. This method sounds simple, but it has a few issues.
First, it depends on the recipient enabling images in their email. If they don’t, the pixel never loads, so the open isn’t tracked, even if the person read the email. Conversely, some email clients or devices preload images, triggering a false open even if the email was never read. Plus, these days, privacy settings like Apple’s Mail Privacy Protection make tracking even trickier by automatically loading these pixels regardless of user behaviour.
The Confirmed Open Rate attempts to get a more accurate signal by adding a second layer of confirmation and/or ruling out opens that happened too quickly for a human to open the email. Rather than logging an open based on the tracking pixel alone, COR counts only those opens backed up by a secondary action, like a click. So, if someone opens your email and clicks on a link inside, that’s considered a “confirmed open.”