Why Your Open Rates Don't Tell the Whole Story
Apple's Mail Privacy Protection pre-fetches email images for a large share of inboxes, inflating open rates regardless of whether a human actually read the email. Click-through rate and revenue per email sent are more reliable, since both require an actual action to register.
What to track instead of open rate
- Click-through rate, tied to an actual link click, not an image pre-fetch
- Revenue per email sent, the metric that actually matters for the business
- List health: unsubscribe rate and spam complaints, signaling deliverability risk
What changed in 2021
In September 2021, Apple launched Mail Privacy Protection. It routes emails through proxy servers and preloads their content, including the tracking pixel that records an open, whether or not the person actually reads the message (Litmus on Apple Mail Privacy Protection). At the time, Apple Mail accounted for close to half of all email opens, so open rates across the industry jumped overnight without anyone reading more.
Why this matters for decisions
- A/B tests on subject lines become unreliable when a large share of opens are automatic
- Engagement-based segments ("people who opened in 90 days") fill with people who never read anything
- Send-time optimisation that relies on opens optimises to Apple's servers, not your readers
- Reporting looks healthier than it is
What to track instead
| Metric | Why it is more reliable |
|---|---|
| Click-through rate | Requires a real action |
| Conversion rate and revenue per recipient | Tied to business outcomes |
| Unsubscribe and complaint rates | Show whether content is wanted |
| Replies | Strong signal for B2B and service emails |
Deliverability is the other half
Gmail and Yahoo's bulk sender rules from February 2024 require SPF, DKIM and DMARC authentication, one-click unsubscribe and spam complaints under 0.3% (Resend on Gmail and Yahoo sender rules). A list full of people who never read your emails pushes complaint rates up and inbox placement down. Clean lists regularly based on clicks and purchases, not opens.
If you must report opens, split out Apple Mail opens and treat them separately. Most email platforms can do this.
See email marketing and the three email flows every business needs.