Open rate

What it means

Open rate is the share of delivered emails that recipients opened. It is used to judge subject lines, send times and overall subscriber engagement. If two hundred of a thousand delivered emails are opened, the open rate is 20%.

Measurement relies on a tiny invisible image embedded in the email. When the image loads, the system records an open. The method is imprecise, though: some email clients block images, while others load them automatically even if the person never actually reads the message.

Since 2021, Apple Mail's privacy protection in particular has distorted open rates by preloading email content through Apple's own servers, so opens are recorded almost always for those users. Today, click-through rate is therefore watched more closely as a sign of genuine interest.

How it works in practice

Open rate is still useful for comparisons within your own campaigns, for example in A/B testing subject lines. If one subject version achieves a clearly higher open rate with the same audience, it is probably more appealing, even if the absolute numbers are inflated.

Open rate is influenced by sender name, subject line, preview text, send time and list quality. A newsletter sent to people who signed up via double opt-in and receive relevant content usually has a higher open rate than a purchased list of addresses.

A persistently low open rate may indicate deliverability problems, with messages ending up in spam. Then check the domain's technical settings, remove inactive contacts and reduce frequency. In lead nurturing, opens are also used to adjust the next content.

What to watch out for

Open rates cannot be compared with other companies' or industries' figures without context. The share of Apple users, the type of content and the measurement method in the specific tool all matter. Decisions should rest on your own trends and above all on clicks and conversions.

Tracking opens is processing of personal data, and under some interpretations it requires consent, much like cookies. The privacy policy should mention that emails contain tracking elements, and switching tracking off for those who object is worth considering.