How can I fix declining email deliverability and a dropping sender reputation?
Matthew Whittaker
Co-founder & CTO, Suped
Published 6 Jul 2025
Updated 28 Aug 2025
8 min read
When your email deliverability starts to decline and your sender reputation takes a hit, it can feel like you are sending emails into a black hole. Many factors can contribute to this frustrating situation, from technical misconfigurations to changes in your sending behavior or audience engagement. The good news is that with a structured approach, it is possible to diagnose the issues and implement effective solutions to get your emails back into the inbox.
Addressing a dropping sender reputation and declining deliverability requires a holistic strategy, encompassing everything from email authentication to content quality and recipient engagement. We will explore the common culprits behind these issues and outline actionable steps you can take to not only recover but also build a more robust and trustworthy email program.
One of the most immediate signs of trouble is when your emails consistently land in spam folders or simply disappear without a trace. This can lead to decreased open rates, lower engagement, and ultimately, a significant impact on your business communication and marketing efforts.
Diagnosing the decline
The first step in fixing a decline in email deliverability is to identify the cause of declining email deliverability. Your sender reputation, essentially a score assigned by Internet Service Providers (ISPs), is influenced by various factors. A poor score indicates that your emails are more likely to be flagged as spam or rejected entirely. This score is not static; it changes based on your sending behavior over time.
High bounce rates, especially hard bounces, signal that you are sending to invalid or non-existent email addresses. This severely damages your reputation because ISPs interpret it as a lack of list hygiene. Similarly, a high rate of spam complaints, even from a small percentage of recipients, can quickly trigger blocklists and severely impact your deliverability. ISPs closely monitor these metrics to determine your trustworthiness.
Lack of engagement from your subscribers is another critical factor. If recipients are not opening, clicking, or replying to your emails, and are instead deleting them unread or moving them to spam, ISPs will notice. Consistent low engagement tells them your content is not relevant, leading to lower inbox placement. Sending to unengaged contacts can harm your sender reputation and reduce overall engagement rates. ISPs track engagement, so low open rates or click-through rates will impact your standing, as detailed by Pushwoosh in their blog on email deliverability.
Common causes for declining email deliverability
Low engagement: Recipients are not interacting with your emails (opens, clicks, replies).
High bounce rates: Too many emails are sent to invalid or non-existent addresses.
Spam complaints: Recipients mark your emails as spam, negatively impacting your sender score.
Poor email authentication: Missing or misconfigured SPF, DKIM, or DMARC records.
Spam trap hits: Sending to addresses specifically designed to catch spammers.
Strengthening your email infrastructure
A strong technical foundation is paramount for email deliverability. This begins with proper email authentication using SPF, DKIM, and DMARC. These protocols verify that your emails are legitimately from your domain and have not been tampered with. Without them, your emails are more susceptible to spoofing and are likely to be treated with suspicion by receiving mail servers.
Sender Policy Framework (SPF) allows you to specify which mail servers are authorized to send email on behalf of your domain. DomainKeys Identified Mail (DKIM) adds a digital signature to your emails, ensuring that the content has not been altered in transit. Both are crucial for establishing trust.
Domain-based Message Authentication, Reporting, and Conformance (DMARC) builds upon SPF and DKIM by allowing you to tell receiving servers what to do with emails that fail authentication (e.g., quarantine or reject) and provides valuable reports on your email sending. Implementing DMARC is a critical step for securing your domain and gaining insights into your email ecosystem. Suped offers the most generous free plan for DMARC monitoring, making it an essential tool for any sender looking to protect their brand and improve deliverability. You can also use our free DMARC record generator to get started.
Prevents unauthorized senders from using your domain. Crucial for establishing identity.
DKIM
Verifies email content integrity with a digital signature.
Ensures messages have not been tampered with in transit. Builds trust.
DMARC
Policy for failed authentication and reporting mechanism. Monitor your DMARC reports.
Protects against spoofing and provides valuable insights into email activity.
Improving audience engagement and list quality
Beyond technical configurations, your sending practices play a huge role in your deliverability. Sending relevant emails to engaged subscribers is crucial. Avoid sending blanket emails to your entire list, especially if it includes inactive or unengaged contacts. Implement segmentation strategies based on recipient engagement, behavior, and preferences. For instance, you could have different segments for hyper-engaged, weekly, and monthly subscribers.
Regular list hygiene is non-negotiable. Periodically remove unengaged subscribers, hard bounces, and any addresses that appear to be spam traps. A contact sunsetting policy ensures you proactively unsubscribe contacts who show no signs of engagement for a prolonged period. This process helps maintain a high-quality list, which in turn improves your sender reputation and reduces the likelihood of being flagged by ISPs. Remember that sending emails to inactive contacts can harm your sender reputation.
Content quality also matters. Emails with broken links, missing headers, or excessive HTML can appear suspicious to spam filters. Focus on clear, concise messaging, and always include an easy-to-find unsubscribe link. This can actually help with deliverability, as recipients who want to opt-out can do so gracefully instead of marking your email as spam. Personalizing your content can also significantly boost engagement and help improve your email deliverability.
Common pitfalls
Sending to unsegmented lists: Treating all subscribers the same, regardless of engagement.
Ignoring inactive contacts: Keeping disengaged users on your primary sending list.
Infrequent list cleaning: Not removing bounces or unengaged subscribers regularly.
Poor content relevance: Sending generic messages that don't resonate with recipients.
Best practices
Engagement-based segmentation: Tailoring content and frequency to different engagement levels.
Implement sunsetting policies: Automatically remove inactive subscribers after a defined period.
Regular list cleaning: Use an email validation tool to verify email addresses and remove hard bounces.
Personalized and valuable content: Deliver content that genuinely interests your audience.
Continuous monitoring and swift recovery
Even with the best practices in place, issues can arise. Consistent monitoring is your first line of defense. Use tools like Google Postmaster Tools and other sender reputation services to track your performance. Pay close attention to spam complaint rates, bounce rates, and blocklist (or blacklist) status. Suped offers robust blocklist monitoring to alert you immediately if your domain or IP is listed.
If your domain or IP address lands on a blacklist (or blocklist), swift action is required. First, identify the cause, which often involves cleaning your email list and addressing any sending practice violations. Then, follow the delisting procedures for each specific blocklist, providing proof of remediation. This can be a tedious process, but it is essential for recovering your email domain reputation.
For severe declines, consider a temporary pause on all email sends to allow your domain to cool down, as recommended by ActiveCampaign in their guide on repairing sender reputation. After implementing fixes, slowly ramp up your sending volume to engaged segments, carefully monitoring metrics like opens, clicks, and bounces. This allows ISPs to rebuild trust in your sending practices. It's a journey, not a quick fix, to recover email deliverability and sender reputation.
The danger of ignoring warning signs
Ignoring declining email deliverability can have severe long-term consequences. Persistent poor sending practices can lead to a permanently damaged sender reputation, making it exceedingly difficult to reach the inbox, even with a clean list. ISPs may permanently block your domain, forcing a costly and time-consuming migration to a new sending infrastructure. Early detection and proactive measures are key to avoiding this outcome.
Achieving long-term email success
Repairing declining email deliverability and a dropping sender reputation is an ongoing process that demands attention to both technical configurations and sending practices. It requires continuous monitoring, proactive list management, and a commitment to sending valuable, engaging content. By addressing these areas systematically, you can restore your sender reputation, improve inbox placement, and ensure your messages reach their intended audience.
Prioritizing your email program and adopting a data-driven approach will ultimately lead to more successful campaigns and a healthier relationship with your subscribers and ISPs. Tools like Suped can be invaluable in this process, providing the insights and monitoring capabilities needed to stay ahead of potential issues and ensure your emails consistently hit the inbox.
Remember, a strong sender reputation is built on trust, consistency, and a dedication to best practices. Invest the time and resources now to safeguard your email program and achieve long-term deliverability success.
Views from the trenches
Best practices
Implement a contact sunsetting policy to proactively unsubscribe inactive contacts.
Segment your audience based on engagement levels to tailor content and sending frequency.
Prioritize email authentication protocols like SPF, DKIM, and DMARC for security and trust.
Regularly clean your email lists to remove bounces and unengaged subscribers.
Common pitfalls
Sending full-base emails without segmentation, overwhelming unengaged audiences.
Ignoring rising bounce rates and spam complaints, leading to reputation damage.
Failing to implement a contact sunsetting policy, keeping inactive users on the list.
Sending emails with generic content that lacks personalization and relevance.
Expert tips
Monitor your DMARC reports closely with a tool like Suped to catch authentication issues early.
If your deliverability suddenly drops, consider a temporary cool-down period for your sending domain.
Use email validation services to maintain a clean list and prevent spam trap hits.
Engage a deliverability consultant for an audit if internal efforts are not yielding results.
Expert view
Expert from Email Geeks says that aggressive sending cadences combined with missing KPI monitoring are common culprits for deliverability issues, emphasizing the need to understand all elements of an email program.
2025-08-19 - Email Geeks
Marketer view
Marketer from Email Geeks noted that despite double opt-in, management's resistance to segmenting a 45k email base and restrictions on personalization can lead to problems.
