How to identify the cause of declining email deliverability and improve it?

Key findings

• Measurement challenges: Initial diagnosis often stems from observing decreased click rates or elevated spam complaint rates, but pinpointing the exact deliverability issue (e.g., inbox placement versus outright blocking) requires deeper analysis.
• Root cause analysis: A decline is rarely due to a single factor. It could be related to list acquisition practices, content issues, authentication failures, or even systemic problems with your email program's overall strategy.
• Time to recovery: The timeline for improvement varies widely. Simple fixes (like authentication errors) might show results in weeks, while issues stemming from poor list quality or fundamental business model flaws could take months or even prove insurmountable.
• Data-driven diagnosis: Leveraging data from your email service provider (ESP) and tools like Google Postmaster Tools is crucial for understanding specific patterns of behavior observed by ISPs.

Key considerations

• Understand your metrics: Go beyond open and click rates. Investigate bounce rates (hard vs. soft), spam complaint rates, and sender reputation scores. For more on improving your overall deliverability, refer to our guide on how to diagnose email deliverability issues.
• Audit acquisition channels: Poor list acquisition is a common culprit. If you're acquiring subscribers through new channels or methods, closely examine the quality of leads and their engagement with your initial emails.
• Implement strong authentication: Ensure your SPF, DKIM, and DMARC records are correctly configured. These are fundamental for establishing sender trust. For a comprehensive overview, see this email deliverability guide.
• Review engagement and content: Low engagement or high spam complaints can signal content issues or mismatched subscriber expectations. Regular list cleaning and a clear sunsetting policy are also vital. Learn more about diagnosing and improving email deliverability and open rates.

Key opinions

• Measurement is key: Marketers emphasize the importance of understanding how deliverability is being measured and what metrics indicate a true decline, distinguishing between spam complaints and actual spam folder placement.
• List quality is paramount: The consensus is that email deliverability success begins with how subscribers are acquired. Purchased lists or poor opt-in practices are major red flags that can lead to persistent issues.
• Acquisition strategy impact: A shift in subscriber acquisition channels or methods can directly impact spam complaint rates and overall deliverability, even for opt-in flows.
• Engagement signals: Higher spam complaint rates, counterintuitively, can indicate that emails are still reaching the inbox but are unwanted, suggesting a content or expectation mismatch.

Key considerations

• Deep dive into acquisition: If deliverability drops, marketers should immediately scrutinize their lead acquisition channels and the expectations set during the signup process. This is often the first step to a cleanup plan. For instance, Campaign Monitor suggests looking at factors that affect email deliverability.
• Refine sunsetting policies: After addressing acquisition issues, implementing a tighter sunsetting policy for inactive subscribers can significantly improve list health and sender reputation. This proactive approach helps manage overall email sender reputation.
• Optimize unsubscribe process: Ensure the unsubscribe option is clear and easy to find. If "Mark as Spam" is simpler than unsubscribing, recipients will likely choose the former, harming your reputation. You can read more in our guide on why emails go to spam.
• Evaluate opt-in flows: Review the entire opt-in process, ensuring the message matches expectations set at acquisition, the flow isn't delayed, and there are no security issues causing unconsented sign-ups.

Key opinions

• Comprehensive audits: Experts typically recommend starting with a thorough audit to identify the specific root causes of deliverability decline, rather than relying on generalized solutions.
• ISP behavior patterns: ISPs like Google and Yahoo monitor sender behavior patterns, meaning changes made to improve deliverability can take weeks or months to result in a noticeable shift in reputation.
• Systemic issues: Sometimes, deliverability problems are deeply rooted in the email program's fundamental business model, requiring a reevaluation of core strategies rather than just quick fixes.
• No quick fixes: There's no universal solution or '3-ring binder answer' to deliverability issues. The path to recovery depends entirely on the identified problem and the effectiveness of the implemented advice.

Key considerations

• Seek specialized help: For severe or persistent deliverability issues, consulting with a deliverability specialist can provide the expertise needed for diagnosis, strategy development, and reputation repair. Our page on how email experts troubleshoot deliverability can offer further insights.
• Understand ISP processing: Recognize that ISPs need time to register changes in sending behavior. Short-term mistakes might rebound quicker, but deep-seated issues require sustained effort. Learn more about understanding email deliverability patterns.
• Prioritize root cause: Focus on identifying and addressing the fundamental reasons why emails are going to spam, as this is the only way to prevent recurrence. This involves evaluating your domain reputation and overall health.
• Leverage data tools: Utilize available tools like Google Postmaster Tools for in-depth insights into sender reputation metrics, spam rates, and delivery errors. This data is invaluable for informed decision-making during the recovery process.

Key findings

• Authentication standards: RFCs and other standards strongly recommend implementing SPF, DKIM, and DMARC to prevent spoofing and establish sender authenticity, which directly impacts deliverability.
• Sender reputation metrics: Documentation often outlines that sender reputation is built on factors like spam complaint rates, bounce rates, spam trap hits, and engagement, all of which ISPs use to filter mail.
• List hygiene importance: Maintaining a clean and engaged subscriber list is repeatedly emphasized as critical. Sending to invalid or unengaged addresses significantly degrades reputation and triggers spam filters.
• Content best practices: Guidelines suggest that relevant, personalized, and high-quality content leads to better engagement, which in turn signals positive sender behavior to ISPs.

Key considerations

• Adhere to authentication protocols: Ensure your email authentication records (SPF, DKIM, DMARC) are correctly implemented and monitored. This is a non-negotiable step for modern email deliverability. For a simpler understanding, refer to a simple guide to DMARC, SPF, and DKIM.
• Monitor blocklists: Regularly check if your IP or domain is listed on any public or private blocklists (also known as blacklists), as this can severely impact delivery. Our in-depth guide to email blocklists explains more.
• Beware of spam traps: Documentation often warns against hitting spam traps, which are email addresses used by ISPs to identify spammers. This reinforces the need for rigorous list hygiene. You can learn more about spam traps and how they work.
• Maintain engagement: ISPs prioritize messages from senders with good engagement. This means sending relevant emails to an interested audience, rather than just focusing on volume. Mailgun provides useful insights on improving your email delivery rate.