Is splitting email lists into high and low engagers an effective strategy for improving deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 13 Aug 2025
Updated 16 Aug 2025
8 min read
The idea of splitting your email list into segments of high and low engagers, then sending campaigns to the high engagers first, has been a topic of debate in the email deliverability world for some time. The premise is straightforward: by sending to your most active subscribers first, you generate positive engagement signals, which theoretically improve your sender reputation with ISPs and MSPs (like Gmail and Outlook). This, in turn, is supposed to help ensure that the subsequent send to your less engaged audience also lands in the inbox.
The logic seems sound on the surface. If a large portion of your initial recipients actively open and click your emails, it sends a strong signal to mailbox providers that your content is valuable and desired. This positive interaction could, in theory, create a beneficial halo effect for the rest of your send, potentially allowing emails to less engaged users to bypass spam filters.
However, the effectiveness of this strategy for routine email marketing is not as clear-cut as some might suggest. While it has roots as a tactic for specific deliverability challenges, applying it broadly without understanding the nuances can lead to more complications than benefits.
In this discussion, I will explore the core principles of sender reputation, delve into the reasons why this engagement-based splitting might be used, highlight its potential downsides, and finally, recommend more sustainable and effective strategies for improving your email deliverability.
Understanding sender reputation
Sender reputation is paramount in email deliverability. Mailbox providers assess your sending practices based on a multitude of factors, with user engagement being one of the most critical. This includes positive interactions like opens, clicks, and replies, as well as negative signals such as spam complaints, unsubscribes, and bounces.Higher engagement rates signal to ISPs that your emails are valued by recipients, thereby building a positive reputation for your sending domain and IP address.
ISPs evaluate your reputation holistically, considering your historical sending patterns and how your recipients interact with your emails over time. They don't just look at a single send in isolation. While a spike in positive engagement can temporarily boost signals, consistent, long-term positive behavior is what truly builds and maintains a strong sender reputation. Conversely, consistent negative feedback, even from smaller segments, can incrementally degrade your standing. This is why email list quality is crucial.
A primary goal of any deliverability strategy should be to minimize negative signals. Spam complaints are particularly damaging, as they indicate that recipients view your emails as unsolicited or unwanted, directly impacting your inbox placement. Therefore, managing your sender reputation involves a proactive approach to ensure that your emails are desired and engaged with by the vast majority of your audience.
Key factors for sender reputation
Engagement rates: High opens, clicks, and replies indicate user interest.
Spam complaint rate: Low rates are critical, as complaints significantly harm reputation.
Bounce rate: Excessive hard bounces signal a poor quality list.
Unsubscribe rate: While expected, high rates suggest content irrelevance.
The strategy of sending to highly engaged users first, then to less engaged ones, isn't entirely without merit. In specific situations, particularly when a sender is experiencing deliverability issues like rate limiting or low inbox placement, it can serve as a reputation rehabilitation tactic. The idea is to flood ISPs with positive engagement from your most responsive segment, effectively warming up your sending reputation before attempting to deliver to a broader, potentially less responsive audience.
This phased approach aims to leverage initial positive feedback to improve the overall impression your sending domain makes on filters. By prioritizing recipients who are most likely to open and click, you're trying to send the strongest possible signal of legitimate, desired mail, which can sometimes help overcome existing deliverability hurdles. It's about optimizing the initial interaction to influence subsequent deliveries.
However, it's crucial to understand that this is often a temporary or conditional strategy, not a sustainable daily practice. Relying on it constantly can mask underlying list hygiene issues or content relevance problems, ultimately hindering long-term deliverability. It's a method for recovery or specific technical challenges, not a substitute for sound email marketing fundamentals.
The perceived benefit
Boost initial engagement: High opens/clicks from top segment.
Warm up sending reputation: Positive signals to ISPs and MSPs.
Increase inbox placement: Help less engaged users reach the inbox.
The practical reality
Temporary fix: Not a long-term solution for deliverability issues.
Masks deeper problems: Avoids addressing list quality or content relevance.
Increases complexity: More segments and sends to manage for minimal gain.
Potential pitfalls and risks
While the intention behind splitting lists by engagement is often good, several pitfalls can arise, especially if this strategy is applied routinely. One major concern is the fragmentation of your data and the increased management overhead. Juggling multiple, slightly different segments for the same campaign can be time-consuming and prone to errors, particularly for small businesses or those new to advanced segmentation.
More importantly, mailbox providers ultimately assess your overall sending reputation. If your less engaged segments generate a higher number of spam complaints or other negative signals, those still count against your domain's reputation in aggregate. A few complaints from a small segment might seem insignificant, but accumulated over time, they can lead to your domain being put on a blocklist (or blacklist), affecting all your sends.
This strategy can also prevent you from addressing the root cause of low engagement: content relevance or list quality issues. Instead of proactively cleaning your list or refining your content strategy, you might be tempted to use this splitting method as a band-aid. True improvement comes from understanding why your emails go to spam and making fundamental changes.
Issue
Impact on deliverability
Increased management complexity
Higher chance of errors and inconsistent sending patterns.
Fragmented reputation signals
Negative feedback from any segment still affects the entire domain reputation.
Avoids root cause analysis
Delays addressing poor list quality or irrelevant content.
Diminished return on investment
Spending resources on unengaged subscribers yields low returns.
Better strategies for deliverability
Instead of relying on complex segmentation schemes for reputation management, focus on consistent list hygiene. Regularly identify and remove inactive subscribers who haven't opened or clicked your emails in a significant period (e.g., 90-120 days). While it might seem counterintuitive to shrink your list, a smaller, highly engaged list almost always performs better and has superior deliverability than a large, stagnant one. Quality over quantity is key.
True segmentation based on subscriber behavior, preferences, and demographics is far more effective. This allows you to send highly relevant content to specific groups, which naturally leads to higher engagement rates and fewer spam complaints. For example, segmenting by product interest, past purchases, or geographic location allows for personalization that resonates with recipients. This proactive approach strengthens your sender reputation organically. You can learn more about how segmentation impacts deliverability.
Ultimately, the best strategy for improving deliverability is to consistently send valuable, desired content to an engaged audience. Focus on clear opt-in processes, relevant messaging, and a well-maintained list. This builds a strong, long-term sender reputation that ensures your emails reliably reach the inbox without needing complex, multi-tiered sending tactics based solely on engagement levels for a single campaign. Consider these tips for increasing email deliverability.
Conclusion
Splitting your email list into high and low engagers for staggered sends is a tactic that can be effective in very specific, limited circumstances, typically as a reputation rehabilitation strategy. However, it is generally not recommended as a standard, ongoing practice for improving email deliverability.
The core issue is that while initial positive engagement helps, ISPs and MSPs assess your sender reputation based on long-term, aggregate data, not just isolated sends. Negative signals, such as spam complaints or bounces, from any segment will still contribute to your overall reputation. Over-segmentation also adds unnecessary complexity to your email marketing operations.
For sustainable deliverability improvements, focus on robust list hygiene practices, genuine behavioral segmentation, and consistently delivering valuable content. These foundational elements will build a strong sender reputation that ensures your emails consistently reach the inbox.
Views from the trenches
Best practices
Maintain consistent and proactive email list hygiene.
Prioritize sending relevant content to genuinely interested subscribers.
Segment lists based on behavior, preferences, or demographics for true personalization.
Common pitfalls
Using engagement-based splitting as a routine strategy instead of a targeted fix.
Ignoring underlying issues like poor list quality or irrelevant content.
Adding unnecessary complexity to email campaigns without significant deliverability gains.
Expert tips
Focus on building a highly engaged list through clear opt-in and value-driven content.
Segmenting for specific content needs is more effective than for deliverability alone.
Address negative feedback proactively; even a few complaints add up over time.
Marketer view
Marketer from Email Geeks says splitting lists can lead to higher spam, unsubscribe, or bounce rates for smaller segments, making management more complex with little overall benefit.
2023-06-02 - Email Geeks
Marketer view
Marketer from Email Geeks says ISPs review every send, but focus on long-term consistency and patterns rather than isolated incidents. A few complaints on a smaller segment might not severely impact reputation unless it is a persistent, high-percentage issue.
Gmail and 
Outlook). This, in turn, is supposed to help ensure that the subsequent send to your less engaged audience also lands in the inbox.
return on investment
reputation rehabilitation strategy. However, it is generally not recommended as a standard, ongoing practice for improving email deliverability.
