> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mailofly.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Open Rates Not Accurate

> Why email open rates may fluctuate due to Apple Mail Privacy Protection (MPP) and security bot pre-fetching.

# Open Rates Not Accurate

Email open rates are calculated by embedding a transparent 1x1 pixel into the HTML body of outbound messages. When the recipient views the email with images enabled, their mail client downloads the pixel and records an open event.

However, modern privacy features and corporate security firewalls can skew open metrics.

***

## 1. Apple Mail Privacy Protection (MPP)

Introduced in iOS 15, macOS Monterey, and watchOS 8:

* Apple Mail pre-fetches and caches all email content (including images and tracking pixels) through Apple proxy servers as soon as the email arrives on the server, **regardless of whether the user opened the email**.
* This causes an artificial **increase** in reported open rates for Apple Mail users.

***

## 2. Security Bot Pre-Scanning

Enterprise email filters (such as Microsoft Defender, Mimecast, and Barracuda) often crawl all incoming links and load images in a virtual sandbox to scan for malware or phishing before delivering the email to the user's inbox.

* This can trigger false open events and automated link clicks within seconds of dispatch.

***

## 3. Image Blocking

Some clients (or users with conservative privacy settings) disable image loading by default. If images are never downloaded, the open pixel does not fire, causing **unrecorded opens**.

***

## Best Practices

* **Focus on Click-Through Rates (CTR)**: Click metrics represent real user intent and are far less susceptible to automated pre-fetching.
* **Track Conversions**: Measure business actions taken inside your application (e.g., logins, purchases) rather than relying solely on raw open metrics.


## Related topics

- [Warm-up Guide](/guides/deliverability/warm-up-guide.md)
- [Deliverability Insights](/sending/deliverability-insights.md)
- [Errors](/api/errors.md)
- [Introduction](/broadcasts/introduction.md)
- [Performance Tracking](/broadcasts/performance-tracking.md)