How to troubleshoot sudden drops in email open rates for a large newsletter?

Summary

Troubleshooting sudden drops in email open rates for a large newsletter involves a comprehensive approach addressing technical aspects, content strategy, and list management. Key areas to investigate include email authentication (SPF, DKIM, DMARC), sender reputation (domain and IP), spam filtering, and list hygiene (segmentation, removal of unengaged subscribers). Tools like Google Postmaster Tools, Microsoft SNDS/JMRP, and GlockApps are recommended for monitoring deliverability metrics. Additionally, analyzing recipient domain data, reviewing content quality and relevance, and actively participating in feedback loops contribute to identifying and resolving deliverability issues.

Key findings

  • Authentication: Correctly implementing SPF, DKIM, and DMARC is essential for email authentication and deliverability.
  • Sender Reputation: Sender IP and domain reputation significantly impact deliverability. Monitor reputation metrics and address any negative trends.
  • List Hygiene: Regularly clean and segment email lists to remove unengaged subscribers and prevent sending to spam traps.
  • Content Quality: Irrelevant or poor-quality content, misleading subject lines, and excessive sending frequency can negatively affect engagement and deliverability.
  • Monitoring: Utilize tools like Google Postmaster Tools, Microsoft SNDS, and GlockApps to monitor deliverability, identify issues, and track performance.
  • Recipient Engagement: Focus on engaging with engaged subscribers to improve sending reputation.

Key considerations

  • Domain Analysis: Break down reporting by recipient domain to identify deliverability issues with specific ISPs.
  • Feedback Loops: Participate in feedback loops to identify and remove subscribers who mark emails as spam.
  • Content Testing: A/B test different email elements, such as subject lines and content, to optimize for engagement and deliverability.
  • Algorithm Changes: Stay informed about changes to email client algorithms that may affect deliverability and adjust strategies accordingly.
  • Proactive Approach: Implement a proactive approach to monitoring and addressing deliverability issues to prevent significant drops in open rates.
  • Opt-In Process: Implement confirmed or double opt-in.

What email marketers say
9Marketer opinions

Sudden drops in email open rates for large newsletters can stem from a variety of factors. Key areas to investigate include technical aspects like domain and IP reputation, authentication (SPF, DKIM, DMARC), and bounce/spam complaint rates. Content-related issues, such as irrelevant subject lines, sending frequency, timing, and lack of engaging content, also contribute. Finally, list hygiene through segmentation and removal of unengaged subscribers is crucial for maintaining deliverability and a healthy sender reputation. Monitoring tools and feedback loops can provide valuable insights into potential problems.

Key opinions

  • Reputation: Check domain and IP address reputation using tools like Sender Score or ReputationAuthority. Low reputation affects inbox placement.
  • Authentication: Ensure SPF, DKIM, and DMARC are correctly set up to authenticate emails and improve deliverability.
  • List Hygiene: Segment email lists and regularly remove unengaged subscribers to prevent sending to inactive addresses and spam traps.
  • Content: Optimize subject lines and email content to provide value and relevance to subscribers. Review and adjust sending frequency and timing.
  • Engagement: Monitor bounce rates and spam complaints to identify and address deliverability issues promptly.

Key considerations

  • ESP Reporting: Leverage your Email Service Provider's reporting tools to analyze deliverability metrics and identify potential issues.
  • Testing: A/B test different email elements (subject lines, content, send times) to optimize engagement and deliverability.
  • Algorithms: Stay informed about changes in email client algorithms that may impact open rates and adjust sending strategies accordingly.
  • Segmentation: Segment your email list to target the right audience to increase open rates, conversions, and engagement.
  • List Cleaning: Clean your email list to improve deliverability by removing inactive and unengaged subscribers.
Marketer view

Email marketer from Campaign Monitor emphasizes that regular email list cleaning should be done in order to remove inactive subscribers. This should improve deliverability by not sending to old addresses and spam traps.

April 2021 - Campaign Monitor
Marketer view

Email marketer from Reddit explains that engagement might drop because of algorithm changes. Review subject lines, content, and sending frequency. A/B test different elements. Check deliverability using a tool such as GlockApps.

February 2025 - Reddit
Marketer view

Marketer from Email Geeks suggests checking statistics for generalized issues or issues over a specific recipient domain, checking domain and IP address reputation and blacklists, asking the ESP about the IP pool, and investigating changes in communications or marketing strategy.

April 2023 - Email Geeks
Marketer view

Email marketer from Mailchimp responds that a sudden drop can be caused by changes in your sending habits, changes to email client algorithms, or a sudden increase in bounces or spam complaints. Segmenting and cleaning lists is key.

November 2022 - Mailchimp
Marketer view

Email marketer from ActiveCampaign shares that segmenting subscribers based on their interests and behaviors helps increase open rates, as well as improve conversions, and reduce unsubscribe rates. When recipients receive highly targeted content that is relevant to their persona, they are more likely to engage.

August 2021 - ActiveCampaign
Marketer view

Email marketer from NeilPatel.com explains that reasons for low open rates include not providing value to the customer, not writing great subject lines, sending emails at the wrong time, sending emails too frequently, and not segmenting your email list. Suggests list cleaning and segmentation.

May 2022 - NeilPatel.com
Marketer view

Email marketer from Litmus explains how the email authentication process is important to ensure deliverability. Setting up SPF, DKIM, and DMARC is essential to ensure that the email reaches the customer's inbox.

February 2025 - Litmus
Marketer view

Email marketer from Email on Acid explains the importance of list hygiene by removing unengaged subscribers and correcting any typos/errors. Monitor bounce rates to ensure email list health.

February 2022 - Email on Acid
Marketer view

Email marketer from HubSpot explains how to improve email deliverability, and to check your sender reputation with Sender Score or ReputationAuthority. If your reputation is low, you will have difficulty reaching recipients' inboxes.

January 2024 - HubSpot

What the experts say
5Expert opinions

Troubleshooting sudden drops in email open rates for a large newsletter requires a multi-faceted approach focused on identifying and addressing reputation issues, improving list hygiene, and proactively monitoring deliverability metrics. Analyzing recipient domains, maintaining a clean email list by removing inactive subscribers, and monitoring domain reputation are crucial steps. Implementing confirmed opt-in processes and actively participating in feedback loops (FBLs) further contribute to a healthy sender reputation and improved deliverability.

Key opinions

  • Recipient Domain Analysis: Break down reporting by recipient domain to identify specific problem areas or ISPs affecting deliverability.
  • Email Reputation: Monitor sender IP reputation, domain reputation, content quality, and complaint rates to diagnose deliverability issues.
  • List Hygiene: Regularly clean email lists to remove inactive subscribers and prevent sending to spam traps.
  • Opt-in Process: Implement a confirmed opt-in process to ensure only engaged subscribers are added to the list.
  • Feedback Loops (FBLs): Participate in FBLs to identify and remove subscribers who mark emails as spam, improving deliverability and protecting sender reputation.

Key considerations

  • Proactive Monitoring: Continuously monitor deliverability metrics and take proactive steps to address potential issues before they significantly impact open rates.
  • Data Accuracy: Ensure accurate and up-to-date WHOIS records for your domain to maintain a positive reputation.
  • Sender Authentication: Ensure proper authentication (SPF, DKIM, and DMARC) is in place and properly configured, as it has a direct effect on deliverability.
  • ISP relationships: Build relationships with ISPs so that they can let you know in advance if there are any issues.
  • ISPs Blacklists: Monitor the status of your sending IPs and domains against the various blacklists.
Expert view

Expert from Word to the Wise explains that domain reputation is crucial for deliverability and is affected by factors such as spam complaints, bounce rates, and engagement. Senders should monitor their domain reputation and take steps to improve it if it's low. They also advise ensuring the WHOIS records are accurate and up to date.

January 2024 - Word to the Wise
Expert view

Expert from Word to the Wise shares that participating in feedback loops (FBLs) is important for identifying and removing subscribers who mark emails as spam. Using FBLs helps improve deliverability and protect sender reputation by preventing future spam complaints.

March 2023 - Word to the Wise
Expert view

Expert from Spam Resource explains that factors impacting email reputation include sender IP reputation, domain reputation, content quality, and complaint rates. Monitor these factors to diagnose deliverability problems.

December 2024 - Spam Resource
Expert view

Expert from Email Geeks suggests breaking down reporting by recipient domain to identify potential issues.

September 2022 - Email Geeks
Expert view

Expert from Spam Resource advises regularly cleaning your email lists to remove inactive subscribers and prevent sending to spam traps. They recommend implementing a confirmed opt-in process to ensure only engaged subscribers are added to the list.

September 2023 - Spam Resource

What the documentation says
5Technical articles

Troubleshooting sudden drops in email open rates involves identifying factors like authentication issues (SPF, DKIM, DMARC), sender reputation, spam filtering, and list hygiene. Tools like Google Postmaster Tools, Microsoft SNDS/JMRP, and GlockApps help monitor domain reputation, spam rates, IP address health, and identify deliverability problems. Examining bounce codes provides insights into authentication failures, spam filtering, or invalid addresses. Maintaining list hygiene by avoiding sending to unengaged users and invalid addresses is crucial.

Key findings

  • Authentication: Authentication issues (SPF, DKIM, DMARC) can significantly impact deliverability and open rates.
  • Sender Reputation: Poor sender reputation, influenced by factors like spam complaints and bounce rates, negatively affects deliverability.
  • List Hygiene: Sending to unengaged users, inactive, or invalid email addresses reduces open rates and harms sender reputation.
  • Spam Filtering: Content triggering spam filters can prevent emails from reaching the inbox, resulting in lower open rates.
  • Monitoring Tools: Tools like Google Postmaster Tools, Microsoft SNDS, and GlockApps provide data to diagnose deliverability issues.

Key considerations

  • Bounce Codes: Examine bounce codes to identify the specific reasons for delivery failures.
  • Feedback Loops: Utilize feedback loops to identify and remove users who mark emails as spam.
  • IP Monitoring: Monitor sending IP addresses for health and potential issues using tools like Microsoft SNDS.
  • Testing: Use email testing tools like GlockApps to assess deliverability across various email providers.
  • Proactive Management: Regularly monitor and address potential issues before they lead to significant drops in open rates.
Technical article

Documentation from SendGrid shares that factors that can negatively impact deliverability include poor sender reputation, high bounce rates, spam complaints, lack of authentication, and sending to inactive or invalid email addresses. Suggests monitoring sender reputation and list hygiene.

July 2021 - SendGrid
Technical article

Documentation from GlockApps explains how to use email testing tools to test deliverability by identifying the root cause of the problems and finding out if the emails are blocked, go to spam or promotions tab. This is done by sending the test emails to multiple seed accounts. A user can then analyze the reports and resolve issues.

May 2022 - GlockApps
Technical article

Documentation from RFC Editor explains how to troubleshoot deliverability issues and that examining bounce codes often provides insight into problems. Look for common error codes to diagnose authentication failures, spam filtering, or invalid addresses.

July 2021 - RFC Editor
Technical article

Documentation from Google explains that sudden drops in open rates can be caused by authentication issues (SPF, DKIM, DMARC), sending to unengaged users, or content triggering spam filters. They recommend using Postmaster Tools to monitor your domain reputation, spam rate, and feedback loop complaints to identify the root cause.

May 2023 - Google
Technical article

Documentation from Microsoft explains that senders can use the Microsoft Smart Network Data Services (SNDS) to monitor the health of their sending IP addresses. Also, they can use the Junk Email Reporting Program (JMRP) to see when users mark their messages as junk.

November 2024 - Microsoft