Passle's CrossPitch email open rates (like many other applications that attempt to track open rates), rely on a small tracking image. If images are blocked, stripped, or cached by email clients or security tools, open rates may not be captured correctly.
Examples of why open rates may not be captured correctly:
By default, Microsoft Outlook blocks automatic image downloads (including tracking images) from anyone not on their Safe Senders list.
Apple’s Mail Privacy Protection (MPP) pre-loads email images, causing the tracking pixel to fire before an actual recipient opens the message.
Gmail loads all email images through Google's proxy. This means that the 'open' notification an email sender receives actually comes from a Google server, not your device directly.
These guidelines aim to help you and your Technical Team colleagues maximise tracking accuracy:
1. Allow remote image loading
Ensure your environment permits loading external images from trusted senders:
- Enable automatic image loading for emails from Passle
2. Proactive security tool adjustments
Check that email gateways or security tools (e.g. Mimecast, Proofpoint, Barracuda, Microsoft Defender) are not:
- Blocking/stripping images (or HTML)
- Prefetching or preloading images
- Sandboxing or scanning remote content
- Rewriting URLs
3. Ensure email clients are not blocking content
For internal Outlook/Exchange environments:
- Ensure no Group Policy is disabling remote images
- Confirm no organisation-wide block is applied to remote assets
4. Known limitations
Even with appropriate mitigation, some open rates may still be less accurate due to:
- Apple Mail Privacy Protection (MPP)
- Gmail and Outlook image caching
- Recipient-level settings that cannot be controlled
Clicks and on-platform actions provide more reliable engagement data - watch this space for upcoming CrossPitch improvements!
Technical Team summary
- Allow images from trusted sources
- Stop security tools from scanning or rewriting images
- Allow external content in email clients
- Avoid stripping images/HTML at gateway level
Please do get in touch with your Client Success Consultant or via support@passle.net if you have any further queries.