Open Rate

Email open rate is calculated as (number of unique opens ÷ number of emails delivered) × 100. If you send 1,000 emails and 250 are opened, your open rate is 25%. It has long been used as the primary indicator of email campaign performance — a high open rate means your subject line worked; a low one means it didn’t. However, the metric has become significantly less reliable since Apple’s Mail Privacy Protection (MPP) was introduced in 2021.

The Apple Mail Privacy Problem

Apple’s Mail Privacy Protection pre-loads email content on Apple devices — including the tracking pixel that registers an “open” — even if the recipient never actually reads the email. This means that for Apple Mail users (a significant portion of email users, often 40–60% depending on your audience), open rates are inflated and no longer accurately reflect actual engagement. Many email marketers have shifted to click-through rate as their primary engagement metric as a result.

Benchmarks

Average open rates vary significantly by industry and whether Apple MPP inflation is accounted for. Pre-MPP, fitness and wellness email campaigns typically saw 20–30% open rates. Post-MPP, raw open rates appear higher but are less meaningful. The most useful benchmark is your own historical performance on the same list — is your rate trending up or down relative to your past sends?

Improving Open Rate

The factors most directly within your control are: subject line quality (personalized, curiosity-inducing, benefit-focused subject lines consistently outperform generic ones), preview text (the 40–100 character snippet that appears next to the subject line in inbox views), send time (testing different days and times for your specific audience), and list hygiene (removing inactive subscribers who drag down your engagement rates).