The counters
| Counter | What it counts |
|---|---|
| Sent | Emails handed to the provider |
| Delivered | Accepted by the receiving server |
| Bounces | Permanently rejected — the address goes to the suppression list |
| Opens | Recipients who loaded the tracking pixel at least once |
| Click rate | Recipients who followed at least one tracked link |
| Unsubscribes | Recipients who left through this campaign |
What an open does not prove
An open is a loaded image. That makes it a floor and a ceiling at once:- clients that block images by default record no open from a reader who read everything;
- privacy proxies that pre-load images record an open from someone who never looked.
The unsubscribe link is never tracked. It does not appear in the clicks-per-link table and
never counts as a click. Neither does the topic opt-out link — a person leaving is not engagement.