Metrics
Updated
Open rate
Definition
Email open rate is the percentage of delivered emails that were opened at least once. It is measured with a tiny tracking image, so it is an estimate, not an exact count.
How it works
Open rate = unique opens / delivered emails x 100. An open is recorded when the email client loads a 1x1 tracking pixel unique to that message.
Since iOS 15 in 2021, Apple Mail Privacy Protection (MPP) preloads images through Apple's servers whether or not the person reads the email, which inflates opens. Gmail's image proxy and corporate security scanners also fetch pixels automatically.
Clients that block images record no open even when the email is read, so open rate can be wrong in both directions.
Example
The raw number overstates real reading. The human rate is closer to it.
Why it matters
Open rate still shows trends: a falling open rate on the same list often means mail is drifting to spam or subject lines stopped working.
Because opens are inflated, they are a weak trigger for automations or list cleaning on their own. Combine them with clicks and replies.
Benchmarks
- Compare your open rate against your own history, not industry averages, which vary widely by audience and are inflated by MPP.
- Watch open rate per mailbox provider. A sudden drop at one provider usually means a placement problem there.
- Use clicks as the primary engagement metric for decisions, and opens as supporting evidence.
- Test subject lines and sender names against each other with A/B tests rather than guessing.
How Lumail handles open rate
Lumail classifies every tracked open as human or bot, flagging Apple Mail privacy prefetches, the Gmail image proxy, security scanners, fast opens and crawlers. The classification is informational: your open rate stays as reported, and the human share is shown beside it.
Opens feed Lumail's engagement score, where a 30% open rate earns the full 50 open points.
Check a real message with the free mail tester or the spam tester.
Frequently asked questions
What is a good email open rate?
It depends on audience, list age and how many recipients use Apple Mail. Compare against your own past sends. A drop of several points on the same list is a stronger signal than any benchmark.
Why is my open rate suddenly so high?
Usually Apple Mail Privacy Protection or security scanners loading the tracking pixel automatically. Look at the human open rate or clicks for real engagement.
Should open rate be calculated on sent or delivered emails?
Delivered is the more accurate base, because bounced emails could never be opened. Check which one your ESP uses before comparing numbers.
Related terms, tools and docs
- MetricsClick-through rateEmail click-through rate (CTR) is the percentage of delivered emails in which at least one link was clicked.
- DeliverabilityEmail deliverabilityEmail deliverability is the ability of your emails to reach recipients' inboxes rather than bouncing or landing in spam.
- List managementList hygieneList hygiene is the routine of removing or suppressing email addresses that hurt deliverability: hard bounces, spam complainers, long-inactive subscribers, invalid addresses and likely spam traps..
- DeliverabilitySender reputationSender reputation is the trust score mailbox providers assign to your sending domain and IP addresses, based on how recipients and their systems react to your mail.
- Free toolFree spam testerCheck an email for the patterns that push mail to spam.
- Free toolFree mail testerSend a real email and get an SPF, DKIM, DMARC and content report.
- DocsBot vs human opensHow Lumail labels automated opens and clicks.
- DocsEngagement scoreOpen and click rates combined into a 0-100 score.
- DocsAutomatic list cleanupUnsubscribe people inactive for 30, 90 or 180 days.
Browse every definition in the email marketing glossary.
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