Blog · August 6, 2026
Why your email tool’s open rate is lying to you
Open tracking works by hiding a 1×1 image in the email. When the recipient's mail app loads that image from our server, we log an open. It sounds precise. It is one of the least reliable numbers in your whole dashboard, and it is contaminated on both ends at once.
Inflated: Apple opens mail nobody read
Since 2021, Apple Mail Privacy Protection pre-loads images the moment a message arrives, before a human looks at it, from Apple's own servers. Every one of those registers as an open. A large slice of your audience is on Apple Mail, so a meaningful share of your “opens” are a machine fetching a pixel in a data centre. Your open rate goes up and means less.
Deflated: blockers and caching hide real reads
At the same time, anyone with images turned off never triggers the pixel, so genuine readers show as never opening. Gmail caches the image through its own proxy, so a person who opens the same email three times may only ever count once. One force pushes the number up, the other pushes it down, and they do not cancel out to something you can trust.
What to do about it
Treat opens as a weak, directional signal, and lean on things that are actually true:
- Replies. A reply is unambiguous. It is the only engagement metric that cannot be faked by a proxy.
- Clicks, with the same caveat as opens but far less prefetch noise, since bots rarely follow links.
- The SMTP response, which tells you whether the message was even accepted for delivery — the thing an open rate silently assumes.
A quick diagnostic
Next time an open rate looks great, ask three questions before you celebrate:
- What share of these opens fired within seconds of delivery? Those are almost certainly prefetch, not people.
- Does the reply rate move with the open rate, or independently? If opens climb while replies do not, the opens are noise.
- Were these messages even accepted — any 4xx deferrals or 5xx rejections hiding underneath the pretty number?
CraftNudge keeps open tracking off by default for exactly this reason, and where it is on, it does not pretend the number is gospel. The receiving server's own response is a far better guide to whether your mail is working.