Email open rate
Email open rate is the share of delivered emails that an email service records as opened, judged by whether a tracking image inside the email was loaded.
How it works
The email service counts an open when a tiny invisible image in the email loads. It misses readers with images off. Apple Mail with Mail Privacy Protection (MPP) loads remote content in the background whether or not the email is read. Such an open may come from the inbox, not a person.
Google does not track open rates and cannot verify other services’ figures. Opens also earn credit for orders: for new accounts, Klaviyo by default credits an order to an email opened in the previous 5 days. Apple privacy opens count too, unless a setting removes them. So an email flow and a Google Ads click can both claim one order, the case covered in email, SMS and Google Ads claiming the same order.
Formula
Emails opened ÷ emails delivered × 100%
Ways to calculate
- Mailchimp also counts a clicked email as opened and can exclude Apple MPP and other bot activity from reports (About Open and Click Rates).
- Klaviyo tags every open with a true-or-false “Apple Privacy Open” flag that segments can filter on (How to identify iOS15 Mail Privacy Protection opens).
Where you see it
In the email service’s report on each email, next to the click rate.
Example
Example store, not client data.
The tableware shop’s newsletter is delivered to 10,000 addresses. The service records 4,500 of them as opened, 2,000 of those only through flagged Apple privacy opens. Open rate = 4,500 ÷ 10,000 = 45%. Without flagged opens: 2,500 ÷ 10,000 = 25%.
Flagged opens may include real readers. Both figures miss readers with images off, so neither is the exact share of people who read it. 300 recipients clicked: a click rate of 3%.
Not to be confused with
- CTR — ad clicks divided by impressions. An email’s click rate divides clicks by delivered emails, and an open is not a click.
- Email deliverability — whether the email reaches the inbox. “Delivered” here only means the mail server accepted it, spam folder included.
Right and wrong readings
- Wrong: “Everyone who opened is an engaged subscriber.” Right: when the Apple flag is true, the inbox may have opened the email, not the person.
Sources
- Mail Privacy Protection & Privacy — Apple: background loading. Checked 2 October 2026.
- How to change your attribution model — Klaviyo: open window, Apple privacy opens. Checked 2 October 2026.
- Email sender guidelines — Google: open rates not tracked. Checked 2 October 2026 (archived copy of 28 May 2026).