Summary
Declining email deliverability is a multifaceted issue stemming from factors such as sender reputation, list hygiene, engagement levels, authentication problems, and opt-in practices. Diagnosing the root cause requires a combination of monitoring tools (like Google Postmaster Tools and Microsoft SNDS/JMRP), analyzing metrics (bounce rates, complaint rates, engagement), testing inbox placement (seed lists), and checking for blocklisting. Improving deliverability involves focusing on explicit permission, transparent opt-in processes, regular list cleaning, engaging inactive subscribers, implementing robust email authentication (SPF, DKIM, DMARC), optimizing content for engagement and avoiding spam triggers, and maintaining consistent sending practices with low complaint rates. Dedicated IP addresses, IP warm-up, custom tracking domains and active monitoring of IP reputation is also crucial for transactional emails. The timeline for improvements can vary greatly depending on the specific issues and the speed of implementing corrective measures.
Key findings
- Multifactorial Issue: Declining deliverability typically results from a combination of factors, not just one single problem.
- Sender Reputation is Key: Maintaining a good sender reputation is critical for ensuring emails reach the inbox.
- Authentication is Essential: Proper email authentication (SPF, DKIM, DMARC) is vital for verifying sender identity and improving inbox placement.
- Engagement Matters: Higher email engagement signals to ISPs that recipients value the emails, leading to better deliverability.
- List Hygiene is Crucial: Regular list cleaning and re-engaging inactive subscribers are essential for maintaining a healthy list and deliverability.
- Opt-in Process Issues: Problems with the opt-in process, such as mismatched messaging or hidden unsubscribe options, can lead to spam complaints.
- Monitoring is critical: Consistent metric and reputation score monitoring is the best way to identify issues.
Key considerations
- Diagnose the Root Cause: Thoroughly investigate the cause of declining deliverability, checking sender score, spam complaints, and blocklists.
- Implement Strong Authentication: Ensure SPF, DKIM, and DMARC are properly configured to authenticate your emails.
- Focus on Permission: Obtain explicit permission from subscribers and set clear expectations about email content and frequency.
- Maintain List Hygiene: Regularly clean your email list and re-engage inactive subscribers.
- Optimize Email Content: Avoid spam trigger words, personalize content, and optimize email design for mobile devices.
- Monitor Deliverability Metrics: Continuously monitor deliverability metrics, feedback loops, and sender score to identify and address issues promptly.
- Use Seed Lists for Testing: Implement a seed list campaign to identify and resolve delivery problems.
- Optimize Opt-In Flow: Optimize the opt-in flow to minimize spam complaints and ensure subscribers expect the emails.
- Consider IP warm-up: For transactional emails, make sure to warm up your IP addresses to ensure maximum delivery.
What email marketers say
11 marketer opinions
Declining email deliverability can stem from various factors, including poor list hygiene, low engagement, authentication issues, and sender reputation. Identifying the root cause involves monitoring sender scores, analyzing spam complaint rates, testing inbox placement with seed lists, and checking for blocklisting. Improving deliverability requires regular list cleaning, engaging inactive subscribers, implementing proper email authentication (SPF, DKIM, DMARC), optimizing content, avoiding spam trigger words, and maintaining a good sender reputation through consistent sending practices and monitoring feedback loops. The timeline for improvement depends on the specific issues and the speed of implementing changes. For transactional emails, dedicated IP addresses and IP warm-up are also important.
Key opinions
- Multiple Factors: Declining deliverability is rarely due to a single issue; it often involves a combination of factors.
- Importance of Authentication: Proper email authentication (SPF, DKIM, DMARC) is critical for verifying sender identity and improving inbox placement.
- Impact of Sender Reputation: Maintaining a good sender reputation through consistent sending practices and low spam complaint rates is crucial.
- Engagement Matters: Higher email engagement signals to ISPs that recipients value the emails, leading to better deliverability.
- List Hygiene: Regular list cleaning and re-engaging inactive subscribers are essential for maintaining a healthy list and deliverability.
- Domain Tracking and IPs: Using a custom tracking domain and dedicated IP addresses will help boost deliverability rates.
Key considerations
- Identify Root Cause: Thoroughly investigate the cause of declining deliverability, checking sender score, spam complaints, and blocklists.
- Implement Authentication: Ensure SPF, DKIM, and DMARC are properly configured to authenticate your emails.
- Improve List Hygiene: Regularly clean your email list and re-engage inactive subscribers.
- Optimize Content: Avoid spam trigger words, personalize content, and optimize email design for mobile devices.
- Monitor Performance: Continuously monitor deliverability metrics, feedback loops, and sender score to identify and address issues promptly.
- Seed Lists: Use seed lists to test inbox placement across different email clients and ISPs.
Marketer view
Email marketer from Email on Acid explains that improving email engagement through personalized content, relevant offers, and interactive elements can positively impact deliverability. Higher engagement signals to ISPs that recipients value the emails, leading to better inbox placement.
6 Feb 2022 - Email on Acid Blog
Marketer view
Email marketer from ActiveCampaign explains that a low sender score will affect your email deliverability rates. Sender score is a reputation score, ranging from 0 to 100, which measures your sending practices and IP address reputation.
22 Jun 2022 - ActiveCampaign
What the experts say
4 expert opinions
Declining email deliverability often stems from issues related to sender reputation, permission practices, and the alignment between acquisition and opt-in processes. Improving deliverability involves understanding the complexities of the problem, adhering to explicit permission protocols, setting clear expectations during signup, and maintaining consistent sending volume with low spam complaint rates. The timeline for seeing improvements can vary greatly depending on the root cause and the effectiveness of the implemented solutions.
Key opinions
- Varied Timelines: The time to improve deliverability can range from very short to never, depending on the problem's nature.
- Importance of Opt-in: Problems with opt-in flows, such as mismatched messaging or hidden unsubscribe options, can lead to spam complaints.
- Permission Practices: Explicit permission and transparent communication about email content and frequency are vital for a healthy sender reputation.
- Sender Reputation Factors: Consistent sending volume, low spam complaint rates, and proper email authentication are essential for a positive sender reputation.
- Acquisition and Opt-in Alignment: A disconnect between user acquisition and the opt-in process contributes to users marking emails as spam.
Key considerations
- Address Opt-in Issues: Ensure opt-in flows are clear, consistent, and offer easy unsubscribe options.
- Focus on Permission: Obtain explicit permission from subscribers and set clear expectations about email content.
- Monitor Sender Reputation: Maintain a positive sender reputation through consistent sending and low complaint rates.
- Problem Diagnosis: Determine the root cause of deliverability issues to implement effective solutions.
- Aquire Quality Leads: Users need to expect an opt-in flow.
Expert view
Expert from Spam Resource explains the importance of sender reputation and the factors that influence it. They highlight that consistent sending volume, low spam complaint rates, and proper email authentication contribute to a positive reputation, which is crucial for ensuring emails reach the inbox.
11 Jul 2024 - Spam Resource
Expert view
Expert from Email Geeks explains that the timeline varies depending on the problem and whether the consultant's advice is followed, with potential outcomes ranging from 30 seconds to never.
7 May 2025 - Email Geeks
What the documentation says
4 technical articles
Email deliverability issues can be identified and improved by leveraging tools and protocols provided by major email providers and industry standards. Google Postmaster Tools and Microsoft's SNDS/JMRP offer insights into sender reputation, spam rates, and authentication status. Implementing SPF, DKIM, and DMARC is crucial for email authentication. Monitoring key metrics like bounce rates, complaint rates, and engagement rates provides valuable feedback on deliverability performance.
Key findings
- Tool Availability: Google and Microsoft offer specific tools to monitor sender reputation and identify deliverability issues.
- Authentication Importance: SPF, DKIM, and DMARC are critical for email authentication and preventing spoofing.
- Metric Monitoring: Key metrics like bounce rates, complaint rates, and engagement rates provide insights into deliverability performance.
Key considerations
- Use Provider Tools: Utilize Google Postmaster Tools and Microsoft's SNDS/JMRP to monitor sender reputation.
- Implement Authentication: Implement SPF, DKIM, and DMARC to improve email authentication.
- Monitor Metrics: Regularly monitor key metrics to track deliverability performance and identify issues.
Technical article
Documentation from RFC Editor explains that implementing SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) is critical for email authentication. These standards help verify the sender's identity and prevent email spoofing, thus improving deliverability.
12 Aug 2024 - RFC Editor
Technical article
Documentation from Microsoft Support explains that Outlook.com users experiencing delivery issues should review their sender reputation using Microsoft's SNDS (Smart Network Data Services) and JMRP (Junk Mail Reporting Program). These tools help identify and resolve issues that affect deliverability to Outlook.com inboxes.
6 Sep 2023 - Microsoft Support
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