Summary
A sudden drop in email open rates after a redesign can be caused by several factors. Potential issues include: problems with how the new design renders across different email clients and devices, content triggering spam filters, negative impacts on sender reputation (due to changes in content or sending patterns), poor list hygiene, irrelevant content, boring subject lines, and Google not pre-fetching images. Technical considerations involve ensuring HTTPS compliance, implementing a proper List-Unsubscribe header, monitoring and responding to feedback loops (FBLs), testing email placement (especially in Gmail), and verifying the provider's event collector is working correctly. Strategic fixes include improving list segmentation, personalizing subject lines, optimizing preview text, ensuring mobile-friendliness, conducting thorough email testing, reviewing email content for spam triggers, and allowing time for machine learning filters to adjust after fixes.
Key findings
- Design Rendering: Inconsistent rendering across email clients and devices can deter opens.
- Spam Filters: Redesigned emails might trigger spam filters due to new content or code.
- Sender Reputation: Sudden changes can negatively impact sender reputation, lowering open rates.
- List Hygiene: Poor list hygiene (inactive subscribers) and irrelevant content decrease engagement.
- Image Pre-fetching: Google might not pre-fetch images for 'new' mail, artificially depressing open rates.
- HTTPS Compliance: Non-HTTPS links and a non-compliant List-Unsubscribe header impact deliverability.
- Subject Lines: Uninteresting Subject Lines have a negative effect on open rates
- Mobile Friendliness: Designs that are not mobile friendly have a negative impact on open rates.
Key considerations
- Test Design: Thoroughly test email design across various clients and devices.
- Review for Spam: Carefully review the email's content and code for spam triggers.
- Maintain List Hygiene: Implement list validation and cleaning to remove inactive subscribers.
- Gmail Placement: Test email placement in Gmail to identify delivery problems.
- Subject Lines: Create engaging, and interesting Subject Lines.
- https Compliance: Ensure links are HTTPS and List-Unsubscribe header is compliant.
- Feedback Loops: Monitor and respond to feedback loops to address complaints.
- Google/Yahoo Compliance: Adhere to Google and Yahoo’s latest email sending requirements.
- Monitor Sender Score: Monitor sender reputation metrics and address any issues.
- Optimize for Mobile: Ensure the new design is mobile-friendly and accessible.
What email marketers say
10 marketer opinions
A sudden drop in email open rates after a redesign can be attributed to a variety of factors. These include issues with how the new design renders across different email clients, triggering spam filters due to changes in content or code, or negatively impacting sender reputation. List hygiene, audience interest, inconsistent sending schedules, and poor subject lines are also contributing factors. Testing the email design across various clients and devices is essential, as are measures to ensure list validation, proper unsubscribe mechanisms, and monitoring sender reputation.
Key opinions
- Design Issues: The new design may not render correctly across all email clients and devices, deterring opens.
- Spam Triggers: The redesigned email might contain elements that trigger spam filters, leading to lower inbox placement.
- Sender Reputation: Changes in sending patterns or content can negatively affect sender reputation, impacting deliverability.
- List Quality: Poor list hygiene (inactive subscribers) and irrelevant content can decrease engagement.
- Subject Line Impact: Poorly written or irrelevant subject lines can lead to lower open rates.
- Mobile Friendliness: If the new design is not mobile friendly, this can lead to lower open rates
Key considerations
- Email Testing: Thoroughly test the new email design across different email clients and devices to ensure proper rendering.
- Spam Filter Review: Review the email's content and code for potential spam triggers.
- List Management: Implement list validation and cleaning practices to remove inactive subscribers.
- Subject Line Optimization: Craft compelling and relevant subject lines that encourage opens; perform A/B testing.
- Sender Reputation Monitoring: Monitor sender reputation and address any identified issues promptly.
- A/B Testing: Experiment with different elements of the email design and content to see what works for your audience.
- Accessibility: Ensure the design is accessible to all users, including those with disabilities.
Marketer view
Email marketer from ActiveCampaign Blog responds that a decrease in open rates after a redesign could be due to the new design being flagged as spam. Review the email's content and code for any potential triggers, and A/B test different elements to see what resonates best with your audience.
4 Sep 2024 - ActiveCampaign Blog
Marketer view
Email marketer from HubSpot Blog explains that a drop in open rates can be caused by changes in list hygiene (more inactive subscribers), shifts in audience interest, or deliverability problems. Redesigning emails might introduce code issues affecting how emails are received and displayed, potentially triggering spam filters.
1 Mar 2025 - HubSpot Blog
What the experts say
8 expert opinions
A sudden drop in email open rates after a redesign could stem from several technical and strategic issues. Google potentially not pre-fetching images for 'new' mail, non-HTTPS links, and a non-compliant List-Unsubscribe header can negatively impact open rates. Testing email placement in Gmail (inbox, promotions, spam) using new accounts and + addressing can help diagnose deliverability. Furthermore, monitoring and responding to feedback loops (FBLs) is crucial. A boring subject line also results in no opens. It's also key to allow time for machine learning filters to adjust after technical fixes. If reporting is off, consider a problem with the provider's event collector.
Key opinions
- Image Pre-fetching: Google might not pre-fetch images for 'new' mail, artificially depressing open rates.
- HTTPS Compliance: Non-HTTPS links and a non-compliant List-Unsubscribe header can negatively impact deliverability.
- Gmail Placement: Email landing in spam folder indicates delivery problems; inbox/promotions suggests image pre-fetching issues.
- Feedback Loops: Monitoring and responding to feedback loops is essential for maintaining email deliverability.
- Subject Line: Poor subject lines are a reason for decreased open rates.
- Reporting Problems: Potential event collector issues.
Key considerations
- Fix HTTPS Issues: Ensure all links are HTTPS and the List-Unsubscribe header is compliant.
- Test Gmail Placement: Use new Gmail accounts and + addressing to test email placement.
- Monitor Feedback Loops: Consistently monitor and respond to feedback loops.
- Subject Line: Write compelling subject lines for your emails
- Event Collector: Raise a ticket with your ESP if there is a reporting problem.
- Allow Adjustment Time: Give machine learning filters a few weeks to adjust after fixing HTTPS issues.
Expert view
Expert from Email Geeks suggests that Google might not be pre-fetching images for 'new' mail (change IP, change DKIM domain, etc.), which can lower open rates temporarily while filters adjust. She also notes the links aren't https:// and recommends fixing, suggesting this could cause images not to be fetched.
27 Mar 2023 - Email Geeks
Expert view
Expert from Email Geeks advises that there's no reason to stop sending emails, recommends to fix the List-Unsubscribe header and ensure links are https://.
30 Aug 2024 - Email Geeks
What the documentation says
4 technical articles
Email design should prioritize consistent rendering across clients and devices; broken elements deter opens. Sender reputation is crucial; changes in sending patterns or content can negatively affect it. Google Postmaster Tools can monitor reputation, spam rates, and feedback. A proper List-Unsubscribe header is also essential, as well as adherence to the latest requirements from Google and Yahoo, for avoiding spam filters.
Key findings
- Rendering Issues: Inconsistent rendering across email clients and devices can deter opens.
- Sender Reputation: Sudden changes in sending behavior can negatively affect sender reputation and open rates.
- Monitoring Tools: Google Postmaster Tools provides insights into sender reputation, spam rates, and feedback loop complaints.
- List-Unsubscribe Header: A properly implemented List-Unsubscribe header is essential for compliance and avoiding spam filters, especially due to new requirements from Google and Yahoo.
Key considerations
- Design Testing: Thoroughly test email designs across various clients and devices.
- Monitor Sender Score: Consistently monitor sender reputation metrics and address any issues.
- Use Postmaster Tools: Utilize Google Postmaster Tools to track key deliverability metrics.
- Implement List-Unsubscribe: Ensure the List-Unsubscribe header is properly implemented and compliant with current standards.
- Compliance: Adhere to Google and Yahoo’s latest email sending requirements.
Technical article
Documentation from Google Postmaster Tools shares that using Google Postmaster Tools to monitor sender reputation, spam rates, and feedback loop complaints is key to troubleshooting deliverability issues. Significant changes in these metrics after a redesign can point to specific problems.
1 May 2023 - Google
Technical article
Documentation from Validity (formerly Return Path) explains that sender reputation is crucial for email deliverability. Sudden changes in sending patterns or content can negatively affect reputation, leading to lower open rates. Monitor sender score and address any identified issues.
8 Jun 2025 - Validity
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