Why am I still having deliverability issues after cleaning my email list?
Michael Ko
Co-founder & CEO, Suped
Published 22 May 2025
Updated 19 Aug 2025
9 min read
It’s a common frustration. You’ve invested time and resources into cleaning your email list, diligently removing invalid addresses, bounces, and even some unengaged subscribers, yet your emails are still struggling to reach the inbox. It feels counterintuitive, doesn't it? You’ve done the foundational work, so why are deliverability issues persisting? The truth is, while list hygiene is crucial, it’s just one piece of a much larger puzzle. Email deliverability is a complex interplay of many factors, and a clean list, while vital, doesn't automatically guarantee perfect inbox placement.
Many senders believe that if their database is good, meaning free of hard bounces and spam traps, their deliverability should be pristine. However, this definition of a good database often falls short. Deliverability issues often stem from more nuanced aspects of list quality, acquisition, and ongoing management beyond just removing obvious bad addresses. It’s about ensuring recipients genuinely want your mail and actively engage with it.
Let's explore the various other elements that contribute to your email deliverability, even after you’ve cleaned your list. Understanding these factors will help you pinpoint the root causes of your persistent inbox placement challenges.
List quality beyond validation
Even with a clean list, continued issues can arise from less obvious list-related problems. This often includes issues with recipient engagement and how the list was initially built. For instance, if your list contains contacts who didn't explicitly opt-in, or whose engagement has significantly dropped, mailbox providers will notice this lack of positive interaction, regardless of the list's cleanliness.
Spam traps are another critical factor. While some list cleaning services claim to remove all of them, it's virtually impossible for them to catch every single one, as many of these traps are designed to identify senders with poor list acquisition practices. Hitting spam traps can lead to your IP or domain being placed on a blacklist or blocklist, severely impacting deliverability. For a deeper dive, consider reviewing our guide on the different types of spam traps and how they work. Maintaining a healthy email list is an ongoing process that goes beyond a one-time scrub; it requires continuous monitoring and engagement strategies.
Ultimately, your email deliverability is heavily influenced by how your recipients interact with your messages. If they consistently open, click, and reply, mailbox providers see your emails as valuable. Conversely, if emails are deleted without being opened, marked as spam, or simply ignored, your sender reputation will suffer. This is why list quality is often considered the primary factor in deliverability, even if it's a more complex issue than simply removing invalid addresses. According to a Mailgun blog on the importance of email list cleaning, neglect of list hygiene can lead to low open rates, high bounce rates, and blocklisting.
Sender reputation and authentication
Even if your list is technically clean, a poor sender reputation can derail your efforts. Your sender reputation is essentially a trust score given to you by mailbox providers based on your sending history. Factors like bounce rates, spam complaint rates, and engagement metrics all contribute to this score. If your reputation is low, emails might go to spam or be rejected outright, regardless of how meticulously you’ve scrubbed your list.
Proper email authentication is fundamental to building and maintaining a good sender reputation. This includes setting up and configuring SPF, DKIM, and DMARC records correctly. These protocols verify that your emails are legitimate and prevent spoofing. A misconfigured or missing DMARC, SPF, or DKIM record can cause deliverability failures, even to engaged subscribers. For example, if Microsoft's Outlook or Yahoo Mail detect authentication issues, your emails might be rejected or sent to junk. You can improve your email reputation and deliverability by ensuring these are correctly implemented.
A robust DMARC policy, moving beyond p=none, can significantly enhance your domain's trustworthiness. Monitoring your DMARC reports helps you identify and fix authentication failures, which are often silent deliverability killers. You can find simple DMARC examples to start with a p=none policy and gradually move to stricter enforcement. Neglecting these technical aspects means even a perfectly clean list won't reach its full potential for inbox placement.
Importance of authentication
Mailbox providers heavily rely on SPF, DKIM, and DMARC to verify sender identity and combat phishing and spam. A misconfigured record, or lack thereof, can lead to immediate filtering or rejection, regardless of list health.
Even with a clean list, authentication failures signal to ISPs that your emails might not be trustworthy, affecting your sender reputation and deliverability.
Content quality and recipient engagement
Beyond the technical configurations, the content of your emails plays a significant role in deliverability. Even with a clean list, if your content triggers spam filters, your emails won't reach the inbox. This includes using too many spammy keywords, excessive images, broken links, or an imbalanced text-to-image ratio. Personalized and relevant content, on the other hand, encourages engagement, which in turn boosts your sender reputation.
Sending frequency and volume are also critical. Even if your list is clean, sending too many emails too frequently can overwhelm subscribers and lead to increased unsubscribes or spam complaints. This signals to mailbox providers that your content might be unsolicited or unwanted, impacting your sender score. It’s about finding the right balance that keeps your subscribers engaged without causing fatigue.
Recipient engagement metrics are paramount. Mailbox providers track how subscribers interact with your emails: opens, clicks, replies, forwards, and even how long they spend reading your email. Low engagement rates, coupled with a higher rate of negative actions like deleting without opening or marking as spam, will hurt your sender reputation over time. Regularly re-engaging stale subscribers (or removing them) is vital to maintain a healthy and active list, which directly influences your deliverability. Learn how to re-engage stale email subscribers for improved deliverability.
Content and engagement best practices
Personalize content: Tailor emails to individual recipient interests and behaviors to increase relevance and engagement. This boosts open and click rates, signaling positive intent to ISPs.
Optimize frequency: Avoid over-sending. Find the optimal sending cadence that keeps subscribers engaged without leading to fatigue or increased complaints. Regularly review your analytics.
Encourage interaction: Include clear calls-to-action (CTAs) that encourage clicks. Prompting replies or adding to contacts can further signal engagement. Ensure your email click-through rate is healthy.
Technical infrastructure and ip/domain reputation
Your sending infrastructure and technical setup can also be a hidden culprit. This includes the reputation of your sending IP address and domain. If you are on a shared IP address, the sending practices of other users on that IP can negatively affect your deliverability, even if your own list is pristine. A single bad actor sharing your IP can cause collective issues, leading to your emails being marked as spam or blocked. This is particularly true for smaller senders or those using standard ESP plans.
Furthermore, issues with your email service provider (ESP) or how your domain is configured can create problems. This could range from incorrect DNS records, a lack of consistent IP warming (if you’re using a new dedicated IP), or even your ESP having its own deliverability challenges. These technical nuances often go unnoticed because they are not directly related to the cleanliness of your contact list. You can explore common reasons why your emails fail for more detailed information.
Finally, being listed on an email blacklist (or blocklist) can severely impede your deliverability. While cleaning your list helps reduce the chances of hitting spam traps, it doesn't automatically remove you from existing blocklists. You need to actively monitor various blocklists and request delisting if your domain or IP is listed. Understanding how email blacklists actually work is crucial for proactive management. This comprehensive view of your email infrastructure is essential to diagnose and fix lingering deliverability problems.
Views from the trenches
Best practices
Implement double opt-in for all new subscribers to ensure high quality and engaged contacts from the start.
Regularly segment your email list based on engagement levels and tailor content to each segment.
Monitor your sender reputation using tools like Google Postmaster Tools and other monitoring platforms.
Ensure all email authentication protocols, including SPF, DKIM, and DMARC, are correctly configured.
Actively track your bounce rates, complaint rates, and engagement metrics to identify issues early.
Common pitfalls
Believing that one-time list cleaning is a complete solution for all deliverability problems.
Failing to implement proper opt-in processes, leading to low-quality or non-consenting subscribers.
Ignoring recipient engagement metrics, focusing only on list size rather than quality.
Neglecting to monitor IP and domain reputation, allowing issues to escalate unnoticed.
Sending emails with generic or irrelevant content that does not resonate with your audience.
Expert tips
Consider real-time email verification at the point of sign-up to catch mistyped addresses immediately.
Focus on nurturing existing subscribers to maintain high engagement rather than constantly acquiring new ones.
Develop a comprehensive re-engagement strategy for inactive subscribers before deciding to remove them.
Segmenting your audience can significantly improve engagement as you tailor content to specific interests.
Always test your email campaigns before a full send to catch potential spam triggers or broken links.
Marketer view
A marketer from Email Geeks says they encounter clients who believe their database is good because they mail daily and clean their lists monthly, but still face deliverability issues because list cleaning isn't a silver bullet.
2020-07-15 - Email Geeks
Marketer view
A marketer from Email Geeks says that while list problems are often the root, it's not always the simplest to fix because it involves understanding why recipients react badly to marketing, leading to ISP filtering.
2020-07-15 - Email Geeks
The holistic approach to email deliverability
Cleaning your email list is a crucial first step, but it’s not the only factor determining your email deliverability. Persistent issues often point to a combination of deeper problems related to ongoing list quality, sender reputation, email authentication, content relevance, and technical infrastructure. To achieve consistent inbox placement, you must adopt a holistic approach that addresses all these areas. Continuously monitor your performance, adapt your strategies, and ensure every email you send is genuinely wanted and valued by its recipient.
By understanding that deliverability extends far beyond just list validation, you can diagnose the true causes of your challenges and implement more effective, long-term solutions. It’s an ongoing commitment to best practices that ultimately leads to successful email marketing campaigns. A 2025 Email Deliverability Report underscores that poor deliverability is often a reflection of a sender's broader practices.
Microsoft's Outlook or 
Yahoo Mail detect authentication issues, your emails might be rejected or sent to junk. You can improve your email reputation and deliverability by ensuring these are correctly implemented.
