What are the deliverability consequences of decreasing email metrics due to sending to unengaged subscribers?
Matthew Whittaker
Co-founder & CTO, Suped
Published 11 Aug 2025
Updated 17 Aug 2025
7 min read
When I talk to clients about email marketing, a common challenge arises: the desire for immediate revenue often conflicts with the long-term health of their email program. It's a tricky balance. I've found myself in discussions where the impulse is to "open up the floodgates" and send to everyone on the list, even those who haven't engaged in ages. The reasoning is usually simple: more emails sent, more potential sales.
However, this approach overlooks a critical aspect of email marketing: deliverability. While it might seem counterintuitive to send fewer emails to boost overall performance, the reality is that sending to unengaged subscribers can significantly harm your ability to reach the inbox of even your most valuable contacts. The metrics might look lower at first, but it is a necessary step towards better results.
The direct link between engagement and deliverability
Mailbox providers (like Gmail, Outlook, Yahoo, and others) are constantly analyzing how recipients interact with your emails. They view engagement metrics, such as open rates, click-through rates, and even replies or forwards, as strong signals of your sender reputation. When these metrics decline, especially across a large segment of your list, it tells providers that your emails are less relevant or desired.
This lack of interest can trigger sophisticated spam filters. If a significant portion of your emails goes unopened or unclicked, mailbox providers may start diverting your messages directly to the spam folder, or even reject them outright. This isn't just about a few emails, it impacts your entire sending domain and IP address, making it harder for all your subsequent campaigns to reach the inbox. It creates a negative feedback loop that can be challenging to reverse.
For example, if your open rates on consumer domains start to dip below typical averages, it's often an early indicator that your mail is landing in the spam folder rather than the primary inbox. It's a clear sign that uninterested recipients are effectively teaching mailbox providers to filter your messages, even if those recipients aren't actively marking your emails as spam.
The compounding effect of low engagement
The problem with sending to unengaged subscribers is that it doesn't just lower your average metrics, it actively erodes your sender reputation. Every email sent to someone who ignores it, deletes it without opening, or worse, marks it as spam, chips away at how mailbox providers view your domain and IP. This accumulated negative feedback can lead to more aggressive filtering for all your emails, regardless of the recipient's engagement history.
This is often referred to as a "death spiral" in email deliverability. Once your sender reputation starts to decline, it becomes increasingly difficult to get your emails delivered, even to your most active and engaged subscribers. You might find your emails ending up on a blocklist (or blacklist), which further exacerbates the problem. For more details on how this process works, consider reading this guide on how email blacklists function.
Ultimately, the equation for successful email delivery can be seen as: "Delivered email = wanted email minus unwanted email." If the "unwanted email" volume increases due to sending to unengaged contacts, the overall amount of "delivered email" (that actually reaches the inbox) will inevitably decrease. This directly impacts your return on investment and the effectiveness of your entire email marketing program.
The death spiral of disengagement
Sending to unengaged subscribers often leads to a vicious cycle: as engagement drops, so does your sender reputation. Mailbox providers then filter more of your emails to the spam folder, further decreasing engagement, and the cycle continues. It's a difficult spiral to break once it gains momentum.
Identifying and segmenting unengaged subscribers
To avoid these deliverability pitfalls, it is crucial to proactively identify and manage your unengaged subscribers. Engagement can be defined differently for each business, but typically it involves opens, clicks, and conversions within a specific timeframe (e.g., the last 90, 120, or 180 days). Regularly reviewing your email metrics by recipient domain can provide valuable insights into where your emails are landing and which segments are truly disengaged.
Segmenting your audience based on their engagement level allows you to tailor your sending strategy. Instead of a blanket approach, you can focus your most important campaigns on your highly engaged segments, where deliverability is likely to be strong. For those who haven't opened an email in a while, a specific re-engagement campaign might be appropriate, or you might decide to suppress them from regular mailings entirely. Learning how to manage deliverability when re-engaging inactive email subscribers is key.
Ignoring unengaged contacts can also lead to higher costs with your email service provider, as many platforms charge based on list size. Moreover, it increases the risk of hitting spam traps, which are email addresses specifically designed to catch senders who don't maintain clean lists. Being caught by spam traps can severely damage your reputation and lead to immediate blacklisting (or blocklisting). You can learn more about how email spam traps work here.
Short-term volume chasing
Focus: Maximize immediate send volume to boost perceived revenue.
Risk: High likelihood of increased spam complaints and unsubscribes.
Impact: Deteriorates sender reputation, leading to broader inbox placement issues over time. This can cause significant drops in overall email deliverability.
Metrics: Initial increase in sent emails, but sharp decline in open and click rates, diluting campaign effectiveness.
Long-term deliverability health
Focus: Cultivate an engaged subscriber base for sustained deliverability.
Risk: Requires patience and discipline, with a potential initial drop in list size.
Impact: Builds a strong sender reputation, resulting in consistent inbox placement and higher overall ROI.
Metrics: Healthy open and click rates from a smaller, more responsive audience, indicating better quality engagement.
Strategies to mitigate risks and improve metrics
Improving email deliverability (and by extension, your metrics) when dealing with unengaged subscribers involves a strategic shift from quantity to quality. Regularly cleaning your email list by removing consistently unengaged contacts is a crucial first step. While it might feel counterintuitive to reduce your list size, it ensures that your mailings are going to recipients who genuinely want to receive them.
Implementing robust email authentication protocols like DMARC, SPF, and DKIM is also foundational. These protocols help mailbox providers verify that your emails are legitimate and from an authorized sender, building trust and improving your sender reputation. A correctly configured DMARC record, for instance, tells receiving servers how to handle emails that fail authentication checks, preventing spoofing and unauthorized use of your domain. You can learn more in this simple guide to DMARC, SPF, and DKIM.
Furthermore, focusing on content relevance and personalization can significantly boost engagement. When subscribers receive emails that are tailored to their interests and past interactions, they are far more likely to open and click. This positive engagement sends strong signals to mailbox providers, reinforcing your sender reputation and increasing the likelihood of future emails reaching the inbox.
Frequency at which recipients mark your email as spam.
High rates are a strong negative signal, leading to severe reputation damage and blocklisting (blacklist) risks.
Bounce Rate
Percentage of emails that could not be delivered.
High bounce rates, especially hard bounces, indicate poor list hygiene and can hurt sender reputation.
Views from the trenches
Best practices
Regularly clean your email list by removing unengaged subscribers.
Segment your audience based on engagement levels to tailor sending strategies.
Implement email authentication protocols like DMARC, SPF, and DKIM to build trust.
Focus on content relevance and personalization to boost subscriber engagement.
Track open and click trends by domain to identify specific deliverability issues.
Common pitfalls
Sending to large, unsegmented lists without considering engagement levels.
Ignoring declining open and click rates, viewing them merely as metrics rather than signals.
Prioritizing immediate send volume over long-term sender reputation health.
Failing to implement or properly configure email authentication protocols.
Not removing or suppressing consistently unengaged subscribers, risking spam trap hits.
Expert tips
Understand that low metrics are a signal, not just a result; they indicate deeper deliverability issues.
Emphasize that delivering wanted email requires reducing unwanted email to maintain inbox placement.
Use data and trending graphs to educate stakeholders on the negative impacts of sending to unengaged lists.
Assert your expertise when advising clients against risky sending practices.
Focus on optimizing signup forms and growing organically engaged segments as a healthier alternative to mass sending.
Expert view
Expert from Email Geeks says: If recipients are uninterested, consumer ISPs are more likely to deliver emails to the spam folder, initiating a potential death spiral for deliverability.
2024-06-25 - Email Geeks
Expert view
Expert from Email Geeks says: The real consequences stem from sending unwanted mail that may be reported as spam, not merely from decreased metrics.
2024-06-25 - Email Geeks
Prioritizing long-term deliverability
The pursuit of high email volume, especially by including unengaged subscribers, can lead to a significant decline in overall email deliverability. While the initial goal might be to boost revenue, the long-term consequences of a damaged sender reputation often outweigh any short-term gains. Prioritizing engagement, maintaining a clean list, and understanding your metrics are fundamental to ensuring your emails consistently reach the inbox.
Ultimately, your success in email marketing hinges on building and maintaining trust with mailbox providers and your audience. By focusing on quality over quantity, you not only improve your deliverability metrics but also foster a more engaged and valuable subscriber base, leading to sustainable and profitable email campaigns. It’s about being strategic, not just sending more mail.
Gmail, 
Outlook, 
Yahoo, and others) are constantly analyzing how recipients interact with your emails. They view engagement metrics, such as open rates, click-through rates, and even replies or forwards, as strong signals of your sender reputation. When these metrics decline, especially across a large segment of your list, it tells providers that your emails are less relevant or desired.
