If some opens never show up in your report, that's expected and inherent to how tracking works. Here are the main causes.
Pro tip: lean on click rate over open rate to measure real engagement — it is far more reliable.
How open tracking works
Mailpro inserts an invisible pixel (1×1 image) in every newsletter. When the recipient opens the email, the image loads — the open is recorded.
Why some opens escape
| Cause | Detail |
|---|---|
| Images blocked | Outlook desktop, some corporates |
| Text-only mode | No image = no pixel |
| Corporate antispam | Strips pixel before delivery |
| Preview pane | Reading without a full open |
The opposite effect: Apple Mail Privacy
The flip side: since iOS 15, Apple Mail pre-loads every email — artificially inflating opens. If your rates are above 50%, it is likely due to this.
Truly reliable indicators
- Click rate: intentional and concrete
- Conversion rate: purchase, form, demo
- Bounce rate: list quality
- Unsubscribes: engagement signal
More on the campaign statistics page.
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