The share of delivered emails that were recorded as opened. Email tools count an open when a tiny tracking image in the email loads, which makes the number less reliable than it looks.
Formula
Open rate = unique opens ÷ emails delivered × 100
Example
Meera's festive email is delivered to 8,000 subscribers and records 3,200 opens. Her open rate is 3,200 ÷ 8,000 = 40%.
How you'll hear it
“Open rate went up after the subject line change, but clicks didn't, so I'm not sure people actually read it.”
What it helps you decide
Which subject line or sender name to keep, when to send, and which subscribers to treat as inactive. Because of Apple Mail Privacy Protection, use it with clicks rather than on its own.
Where people misread it
Since 2021, Apple Mail Privacy Protection downloads email content, including tracking images, in the background whether or not the person reads the email, and hides when and how often they opened it. So many recorded opens are machine opens. Mailchimp says MPP can falsely inflate open metrics. Treating opens as 'people who read' leads to wrong subject line winners and wrong inactive lists.
The story
Meera tests two subject lines for her festive email and plans to pick the winner by open rate.
| Emails delivered | 8,000 |
| Opens recorded | 3,200 |
| Open rate | 40% |
|---|
The number looks right. 40% feels healthy, and the subject line seems to be working.
What it hides. Apple Mail Privacy Protection loads the tracking image for Apple Mail users in the background, read or not. Her email tool flags 1,200 of the 3,200 opens as likely machine opens.
| Opens recorded | 3,200 |
| Flagged machine opens | −1,200 |
| Opens likely by people | 2,000 |
| Adjusted open rate | 25% |
|---|
A subject line that wins on opens could simply have gone to more Apple Mail users.
What to look at instead. Clicks and sales. The email got 240 clicks and 40 orders worth ₹80,000. Pick subject lines on click rate when you can, and do not mark someone inactive just because they have no opens; check clicks and purchases first.
All figures are fictional and illustrative.
Work out your open rate, with and without machine opens
The example's numbers are filled in. Replace them with yours.
Use open rate as a rough signal only. Check click rate before deciding a subject line won.
Don't confuse it with
- Click rate: people who clicked a link, a much harder signal to fake.
- CTOR: clicks as a share of opens, not of deliveries.
Related terms
Sources
- About Open and Click Rates, Mailchimp (Intuit)
- Mail Privacy Protection & Privacy, Apple
- Email Marketing Benchmarks & Industry Statistics, Mailchimp (Intuit), 2023