Glossary
What is email open rate?
Email open rate is the share of sent emails recorded as opened. It is measured with a tiny hidden image that loads when an email is displayed. Because many mail apps now load images automatically or block them, open rate is unreliable. Replies and meetings are better numbers.
Published by Sellinger AI. Numbers and settings checked on 19 October 2026 against the fact register. Report an error.
How is it measured?
The sender adds a one pixel image to the email. When the recipient's mail app fetches it, the open is recorded. If the image is blocked, no open is recorded. If a mail app fetches it for the user in advance, an open is recorded that nobody saw.
Why is it unreliable?
- Some mail apps load images automatically, which inflates opens.
- Some block them, which hides real opens.
- Tracking images can hurt deliverability, because they look like marketing mail.
What should you track instead?
| Number | Why |
|---|---|
| Reply rate | A person answered |
| Meetings booked and held | The business result |
| Bounce rate | A list and reputation problem |
| Opt outs | The audience or the message is wrong |
How Sellinger handles it
Sellinger's analytics are built on people reached, replies, reply rate and meetings, with meetings held and no shows counted separately. Automatic replies from helpdesks and no reply senders are marked as machine mail and do not count as a human reply.
Common questions
Is a high open rate good?
Should I turn tracking off?
What is a good reply rate?
Sources and method
Sellinger analytics definitions and machine mail handling in the fact register and the app, checked 19 October 2026.
Related: Reply rate, Email deliverability, Cold email, Reading your analytics.
