Why has my email open rate dropped suddenly and what can I do?

Summary

A sudden drop in email open rates is a multifaceted issue arising from technical configurations, sender reputation, content relevance, and list management practices. Technical aspects involve issues like IP blacklisting, potentially stemming from Sendinblue's shared IP pools, improper DMARC implementation, and ISP-specific filtering. Sender reputation, crucial for deliverability according to Google, Microsoft, and industry experts, is influenced by authentication (SPF, DKIM, DMARC), complaint rates, spam trap hits, and sending volume. Content factors include generic subject lines, spam trigger words, and inconsistent rendering across email clients. List management involves segmenting for relevance, removing inactive subscribers, managing sending frequency to avoid fatigue, and ensuring opt-in consent and value delivery. Re-engagement campaigns and A/B testing are commonly recommended to improve engagement and identify effective strategies.

Key findings

  • Technical Configuration Matters: Improper email authentication (SPF, DKIM, DMARC) and IP blacklisting significantly hurt deliverability.
  • Sender Reputation is Paramount: ISPs like Gmail and Microsoft heavily rely on sender reputation metrics (complaints, spam traps, engagement) for filtering.
  • Content Relevance Drives Engagement: Generic or spammy content leads to filtering or disengagement, lowering open rates.
  • List Segmentation is Critical: Sending irrelevant content to a broad audience decreases engagement and can increase complaints.
  • List Hygiene Improves Deliverability: Removing inactive subscribers enhances sender reputation and overall engagement rates.
  • Testing is Essential: Testing deliverability across different ISP's shows the effectiveness of the deliverability and provide opportunities for areas to improve.

Key considerations

  • Audit Technical Setup: Verify SPF, DKIM, and DMARC records. Investigate if the sending IP is blacklisted. Use Postmaster Tools.
  • Monitor Sender Reputation: Track complaint rates, spam trap hits, and engagement metrics to identify reputation problems.
  • Optimize Email Content: Craft personalized, intriguing subject lines. Avoid spam trigger words. Test rendering across email clients.
  • Segment and Personalize Lists: Segment based on demographics, behavior, and purchase history. Tailor content to specific segments.
  • Implement List Hygiene Practices: Remove inactive subscribers and implement a re-engagement campaign for potentially lost subscribers.
  • Ensure Opt-In and Provide Value: Confirm subscribers opted in and consistently deliver valuable content aligned with their interests.
  • Manage Sending Frequency: Avoid overwhelming subscribers with too many emails, potentially leading to fatigue and unsubscriptions.
  • Review Recent Changes: Review IP's, domains, from addresses and content to see if any changes have had a negative impact. Change these back if appropriate.

What email marketers say
15Marketer opinions

A sudden drop in email open rates can stem from various interconnected issues. These range from technical problems like IP blacklisting or misconfigured DMARC records, especially with providers like Sendinblue, to broader challenges such as changing email client algorithms, increased inbox competition, and poor sender reputation with ISPs. Content-related factors also play a crucial role, including irrelevant or poorly crafted subject lines and preview text, triggering spam filters with certain words, and inconsistent email rendering across devices. Finally, list management practices significantly impact open rates. Sending too frequently, failing to segment lists for relevant content, and neglecting list hygiene (removing inactive subscribers) all contribute to decreased engagement. Re-engagement campaigns and A/B testing are recommended as ways to improve list health and identify optimal messaging strategies.

Key opinions

  • Technical Issues: Blacklisted IPs and incorrect DMARC setups can severely impact deliverability.
  • Algorithm Changes: Email client algorithms are constantly evolving, requiring marketers to adapt their strategies.
  • Sender Reputation: ISPs consider sender reputation when determining whether to deliver emails to the inbox.
  • Content Relevance: Irrelevant or poorly crafted email content leads to decreased engagement.
  • List Hygiene: Inactive subscribers negatively impact sender reputation and open rates.

Key considerations

  • Technical Audit: Check IP reputation, DMARC configuration, and authentication settings.
  • Content Optimization: Improve subject lines and preview text, avoid spam trigger words, and ensure consistent rendering across devices.
  • Segmentation & Personalization: Segment lists based on demographics, behavior, and purchase history and create more personalized content.
  • Frequency & Timing: Optimize send frequency and timing to avoid subscriber fatigue.
  • List Management: Regularly clean your email list to remove inactive subscribers and implement a re-engagement campaign.
  • A/B Testing: Use A/B testing to identify subject lines, send times, and content that resonate best with subscribers.
  • Engagement Analysis: Monitor unsubscribe rates, engagement rates to better target subscribers and assess list health.
Marketer view

Email marketer from Email Geeks (from Sendinblue) clarifies that advising DMARC implementation as a deliverability fix is incorrect and expresses a desire to remove the problematic DMARC record recommendation.

September 2021 - Email Geeks
Marketer view

Email marketer from Email Geeks asks about bounce rates and other signals, suggesting checking Postmaster tools.

August 2023 - Email Geeks
Marketer view

Email marketer from Gmass responds that improving subject lines by making them more personalized, intriguing, and relevant can significantly increase open rates.

March 2023 - Gmass
Marketer view

Email marketer from Mailjet explains that decreased open rates can be due to various factors including changes in email marketing habits, increased competition in the inbox, and alterations in email client algorithms.

April 2022 - Mailjet
Marketer view

Email marketer from Email Geeks explains that encouraging users to implement a DMARC record without the ability to analyze DMARC XML reports or suggesting it as a fix for deliverability is misguided. He clarifies that having a DMARC record in place does not directly improve deliverability.

October 2021 - Email Geeks
Marketer view

Email marketer from StackOverflow shares that avoiding spam trigger words in subject lines and email content can prevent emails from being flagged as spam, increasing the chances of reaching the inbox and improving open rates.

February 2022 - StackOverflow
Marketer view

Email marketer from Email on Acid explains that optimizing email preview text can entice subscribers to open the email. Compelling preview text provides additional context and increases curiosity.

June 2021 - Email on Acid
Marketer view

Email marketer from Email Geeks mentions encountering several users complaining about Sendinblue open rate changes and points out that emails are often sent from a single IP address which may be blacklisted in multiple RBLs (Real-time Blackhole Lists).

April 2021 - Email Geeks
Marketer view

Email marketer from Reddit shares that sending too many emails too frequently can lead to subscriber fatigue and decreased open rates. Reducing the frequency and ensuring valuable content can help improve engagement.

December 2022 - Reddit
Marketer view

Email marketer from Litmus responds that testing emails across different email clients and devices ensures proper rendering and a consistent user experience, preventing subscribers from deleting emails due to formatting issues. This testing can indirectly increase open rates by improving deliverability.

December 2021 - Litmus
Marketer view

Email marketer from Campaign Monitor explains that A/B testing subject lines, send times, and content can identify strategies that resonate best with subscribers, optimizing open rates over time.

November 2021 - Campaign Monitor
Marketer view

Email marketer from ActiveCampaign explains that proper list segmentation based on demographics, behavior, and purchase history ensures subscribers receive relevant content, boosting engagement and open rates.

September 2021 - ActiveCampaign
Marketer view

Email marketer from Sendinblue shares that implementing a re-engagement campaign to target inactive subscribers can improve open rates by removing unengaged users from your primary sending list.

January 2022 - Sendinblue
Marketer view

Email marketer from Email Marketing Forum shares that a high unsubscribe rate can signal that your content is not relevant to your audience. Focus on providing more value or segmenting your list to better target subscribers.

March 2025 - Email Marketing Forum
Marketer view

Email marketer from HubSpot responds that regularly cleaning your email list to remove inactive or unengaged subscribers can improve your sender reputation and overall open rates.

June 2021 - HubSpot

What the experts say
6Expert opinions

A sudden drop in email open rates can be attributed to a combination of factors related to ISP filtering, sender reputation, and changes in email sending practices. Identifying whether the drop is isolated to a specific ISP can indicate filtering issues, suggesting the need to test delivery to different webmail providers. While IP problems might require ESP intervention, bulk foldering is typically unrelated. Understanding the different types of ISPs and their filtering methods is crucial, as engagement metrics vary across providers. Sudden drops in engagement can also be triggered by alterations to the sending IP, domain, 'From' address, or content. It's essential to monitor sender reputation closely. Finally, maintaining list hygiene, ensuring subscribers have opted in, and delivering on promised value are critical for long-term deliverability.

Key opinions

  • ISP-Specific Issues: Open rate drops may be isolated to a specific ISP, indicating filtering problems.
  • Sender Reputation: Sudden changes in sending IP, domain, or content can negatively affect sender reputation and trigger filtering.
  • ISP Diversity: Different ISPs have different filtering methods, with engagement metrics varying across providers.
  • List Hygiene Importance: Maintaining a clean and engaged list is critical for deliverability.
  • Blocklisting: Blocklisting is only one factor that can influence deliverability.

Key considerations

  • ISP Testing: Create new email addresses at different webmail domains to test delivery and identify ISP-specific issues.
  • Sender Reputation Monitoring: Closely monitor sender reputation to identify potential problems.
  • List Opt-In Verification: Ensure all subscribers have explicitly opted in to receive emails.
  • Value Proposition Delivery: Provide valuable content that aligns with subscribers' expectations.
  • Sender Changes Review: Review recent sender changes to determine if there were any changes to IP, domain, 'From' address or content and if so, change it back.
Expert view

Expert from Word to the Wise, Laura Atkins, explains that sudden drops in engagement can be linked to a change of IP, domain, From: address, content or a combination. It is crucial to watch sender reputation closely and that a good volume of mail is needed to establish reputation.

June 2022 - Word to the Wise
Expert view

Expert from Email Geeks details different types of ISPs (Internet Service Providers) and their filtering methods, including free webmail providers (Gmail, Microsoft, Verizon), European providers, cable providers, and businesses using GSuite/O365. She notes that engagement matters differently based on the ISP type.

April 2021 - Email Geeks
Expert view

Expert from Word to the Wise, Dennis Dayman, shares that list hygiene is critical, and it's important to be honest with subscribers about your intentions and what value they will receive. Make sure they opted in, and that you are fulfilling your promise.

October 2021 - Word to the Wise
Expert view

Expert from Word to the Wise, Laura Atkins, responds that Blocklisting is one signal of an issue that can influence deliverability. But other influences include authentication, complaints and how recipients interact with the email. Even if you aren't blocklisted, deliverability can be impacted.

July 2024 - Word to the Wise
Expert view

Expert from Email Geeks explains that at the sender's volume, an IP problem would require the ESP's intervention. However, she notes that if mail is being accepted, IP reputation is likely not the issue, and bulk foldering is rarely related to IP issues.

July 2021 - Email Geeks
Expert view

Expert from Email Geeks suggests investigating if the open rate decrease is specific to one ISP, indicating potential filtering issues. She suggests creating new email addresses at webmail domains to test delivery.

April 2023 - Email Geeks

What the documentation says
3Technical articles

A sudden drop in email open rates is often linked to sender reputation, which is heavily influenced by factors like email authentication, user engagement, sending volume, complaint rates, and spam trap hits. Google, Microsoft, and email standards bodies emphasize the importance of a positive sender reputation for ensuring email deliverability. Implementing SPF, DKIM, and DMARC helps verify sender identity, improving the likelihood of emails reaching the inbox. Failure to maintain a good reputation results in emails being filtered as spam, leading to lower open rates.

Key findings

  • Sender Reputation Matters: Gmail and Microsoft prioritize sender reputation when filtering emails.
  • Email Authentication is Key: SPF, DKIM, and DMARC are essential for verifying sender identity and improving deliverability.
  • Engagement Impacts Delivery: User engagement plays a role in whether emails are delivered to the inbox.
  • Sending Practices Influence Reputation: Sending volume, complaint rates, and spam trap hits significantly impact sender reputation.

Key considerations

  • Implement Authentication Protocols: Ensure SPF, DKIM, and DMARC are properly configured to authenticate emails.
  • Monitor Sender Reputation: Use tools like Google Postmaster Tools to monitor sender reputation metrics.
  • Manage Sending Volume: Gradually increase sending volume to avoid triggering spam filters.
  • Reduce Complaint Rates: Focus on providing valuable content and segmenting lists to minimize complaints.
  • Avoid Spam Traps: Practice proper list hygiene to avoid sending emails to spam traps.
  • Encourage User Engagement: Encourage recipients to mark emails as 'not spam' if they are misclassified.
Technical article

Documentation from Microsoft explains that maintaining a good sender reputation is crucial for email deliverability. Factors such as sending volume, complaint rates, and spam trap hits impact sender reputation and can affect open rates.

October 2023 - Microsoft
Technical article

Documentation from RFC Editor answers that implementing email authentication protocols like SPF, DKIM, and DMARC helps verify the sender's identity and improves email deliverability, which in turn can increase open rates by ensuring emails reach the inbox.

November 2022 - RFC Editor
Technical article

Documentation from Google Postmaster Tools explains that Gmail's spam filter considers factors like sender reputation, authentication, and user engagement to determine whether to deliver emails to the inbox. Poor sender reputation can lead to lower open rates as emails are filtered as spam.

March 2021 - Google Postmaster Tools