- Barbara Mettle-Olympio31 January, 2025
Over the past two years, email marketers across various industries have observed a noticeable decline in engagement. According to the Data & Marketing Association (DMA), average open rates have declined by roughly 20% since 2021. This downward trend isn't random, nor is it simply a matter of “customers losing interest.” The landscape of email delivery, privacy, and consumer behaviour has fundamentally shifted.
At the same time, the rising cost of customer acquisition and tightening privacy restrictions have made the email list one of the most valuable assets in an organisation. We’re not referring here to the bought lists or the scraped contacts, but rather the earned audience. The people who have taken a deliberate action to subscribe, purchase or otherwise signalled a genuine interest in your brand.
This audience costs almost nothing to reach, delivers the highest margins, and, when nurtured properly, drives repeat revenue, reduces churn, and strengthens long-term customer lifetime value. They’re also the people most likely to recommend you, adding a compounding effect that no paid channel can replicate.
So when engagement within this audience starts to decline, it’s far more than a superficial performance issue. It’s a big warning sign that your most cost-effective, highest-intent channel is under strain, and ignoring this risks weakening your brand’s entire growth engine.
In this article, we focus on the 3 factors that, across our client work, repeatedly surface as the core reasons engagement drops.
1: Weak or Non-existent Segmentation
The Pareto Principle
The Pareto Principle, often called the 80/20 rule, states that a small portion of inputs typically drives the majority of outcomes. In practical terms, around 20% of customers, products or activities often generate 80% of results. It's a reminder that value is rarely distributed evenly, and that focusing on the small group that delivers the greatest impact usually produces far better returns than trying to treat every segment the same.
Segmentation issues often emerge when organisations treat their entire contact base as a single or arbitrary groups, rather than a collection of customers with distinct needs, behaviours and motivations.
Behavioural signals such as browsing activity, session history and on-site interactions may be captured but never analysed. Psychographic information, including values, motivations and lifestyle preferences, is rarely incorporated into email workflows because it sits in separate systems or is never transformed into usable, structured segments. Subject lines begin to sound repetitive because they're not tailored to any specific group. Content feels generic because it's designed to appeal to everyone and ends up resonating with no one. Frequency becomes either too high or too low because it's based on internal schedules rather than the natural rhythms of different customer segments.
The irony is that many organisations already possess enough data to create a far more intelligent segmentation strategy. Customer service logs, web analytics, product usage patterns, loyalty programmes, subscription behaviours, survey responses and even payment timing all contain valuable indicators of intent and interest. However, these insights often remain locked within departments or technology platforms that do not integrate with the marketing team.
Pareto’s 80/20 principle reinforces why this matters. In many organisations, 20% of customers drive 80% of value. When segmentation is absent, this high-value segment receives the same messaging as lower-value or inactive groups. The consequence is predictable: the most profitable customers become harder to reach, easier to lose and less inclined to engage.
Effective segmentation protects this core audience by ensuring they receive more personalised communication that reflects their needs, habits and stage in the customer journey.
Behavioural signals such as browsing activity, session history and on-site interactions may be captured but never analysed. Psychographic information, including values, motivations and lifestyle preferences, is rarely incorporated into email workflows because it sits in separate systems or is never transformed into usable, structured segments. Subject lines begin to sound repetitive because they're not tailored to any specific group. Content feels generic because it's designed to appeal to everyone and ends up resonating with no one. Frequency becomes either too high or too low because it's based on internal schedules rather than the natural rhythms of different customer segments.
The irony is that many organisations already possess enough data to create a far more intelligent segmentation strategy. Customer service logs, web analytics, product usage patterns, loyalty programmes, subscription behaviours, survey responses and even payment timing all contain valuable indicators of intent and interest. However, these insights often remain locked within departments or technology platforms that do not integrate with the marketing team.
Pareto’s 80/20 principle reinforces why this matters. In many organisations, 20% of customers drive 80% of value. When segmentation is absent, this high-value segment receives the same messaging as lower-value or inactive groups. The consequence is predictable: the most profitable customers become harder to reach, easier to lose and less inclined to engage.
Effective segmentation protects this core audience by ensuring they receive more personalised communication that reflects their needs, habits and stage in the customer journey.
2: Poor Value Exchange
A weak value exchange is one of the most significant drivers of declining engagement, and it often sits behind rising email fatigue. Customers open emails when they feel the content genuinely benefits them.
When communication becomes dominated by promotions and offers little meaningful insight, guidance or support, the perceived value drops quickly. Once customers feel that emails consistently take more than they give, even loyal subscribers begin to disengage.
This problem is intensified by the inbox environment customers operate in today. The average person now receives between 100 and 140 emails each day, depending on age and profession. Further research shows that 40% of users delete marketing emails without opening them when brands overcommunicate or repeat the same message formats. The DMA also reports that frequency frustration has become one of the leading reasons consumers unsubscribe, overtaking irrelevant content for the first time. Customers now judge value almost instantly, and anything that feels repetitive or self-serving is deprioritised within seconds.
This imbalance often develops when organisations focus narrowly on short-term commercial performance. Email calendars become filled with sales pushes and tactical announcements, while informative or customer-centred content is gradually reduced. Over time, customers learn to expect little beyond another sales prompt, which weakens trust and encourages delete without open behaviour.
But promotions are not the issue. The issue is the lack of a broader mix of value. High performing programmes combine commercial intent with content that teaches, reassures or supports. Many organisations underestimate the material they already hold that could strengthen their value exchange.
Customer service teams know recurring questions and pain points. Digital teams see where users hesitate or drop off. Product teams understand which features are misunderstood or underused. Data teams can identify behaviour patterns that signal intent. All of these insights could be translated into content that genuinely supports the customer experience, yet they often remain unused because promotional activity takes priority.
When communication becomes dominated by promotions and offers little meaningful insight, guidance or support, the perceived value drops quickly. Once customers feel that emails consistently take more than they give, even loyal subscribers begin to disengage.
This problem is intensified by the inbox environment customers operate in today. The average person now receives between 100 and 140 emails each day, depending on age and profession. Further research shows that 40% of users delete marketing emails without opening them when brands overcommunicate or repeat the same message formats. The DMA also reports that frequency frustration has become one of the leading reasons consumers unsubscribe, overtaking irrelevant content for the first time. Customers now judge value almost instantly, and anything that feels repetitive or self-serving is deprioritised within seconds.
This imbalance often develops when organisations focus narrowly on short-term commercial performance. Email calendars become filled with sales pushes and tactical announcements, while informative or customer-centred content is gradually reduced. Over time, customers learn to expect little beyond another sales prompt, which weakens trust and encourages delete without open behaviour.
But promotions are not the issue. The issue is the lack of a broader mix of value. High performing programmes combine commercial intent with content that teaches, reassures or supports. Many organisations underestimate the material they already hold that could strengthen their value exchange.
Customer service teams know recurring questions and pain points. Digital teams see where users hesitate or drop off. Product teams understand which features are misunderstood or underused. Data teams can identify behaviour patterns that signal intent. All of these insights could be translated into content that genuinely supports the customer experience, yet they often remain unused because promotional activity takes priority.
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3: Lists and Data Hygiene Issues
It’s understandable to want to preserve the size of an email list. As mentioned, an earned audience is one of the most valuable assets an organisation has, and keeping those contacts feels essential. But this instinct can work against the long-term health of the email channel if list and data hygiene are not actively maintained.
When organisations continue sending to unengaged, inactive or invalid contacts just to protect list volume, MAGY receive a consistent signal that the content is low value. High proportions of dormant recipients dilute engagement rates, and inbox algorithms use these patterns to assess whether a sender is still relevant to its users. Over time, this leads to a decline in sender reputation, and that reputation lives at the level of the sending domain, not the individual campaign.
Recent privacy changes make this challenge even more complex. Apple Mail Privacy Protection obscures genuine open behaviour and inflates open rates, making it harder to distinguish between active and inactive subscribers. Without reliable engagement signals, marketers can often continue sending to users who have not interacted for months. Inbox providers prioritise meaningful engagement over list size, so sending to dormant users accelerates the decline in domain reputation. A weakened domain reputation affects whether emails land in the primary inbox, the promotions tab, spam or are quietly suppressed.
Even highly relevant and well-targeted messages may fail to reach recipients because the domain has been deemed low trust. In severe cases, poor domain reputation can spill over into operational emails such as password resets, confirmations or important account notifications, creating risk across the organisation.
Once domain reputation declines, recovery is slow and requires sustained, controlled sending to the most engaged users. During this period, visibility drops, engagement deteriorates further, and the cost of acquisition rises as email becomes less effective at retaining and nurturing customers. So while protecting list size may feel important, keeping data clean to help protect domain reputation is what keeps email viable in the long run.
When organisations continue sending to unengaged, inactive or invalid contacts just to protect list volume, MAGY receive a consistent signal that the content is low value. High proportions of dormant recipients dilute engagement rates, and inbox algorithms use these patterns to assess whether a sender is still relevant to its users. Over time, this leads to a decline in sender reputation, and that reputation lives at the level of the sending domain, not the individual campaign.
Recent privacy changes make this challenge even more complex. Apple Mail Privacy Protection obscures genuine open behaviour and inflates open rates, making it harder to distinguish between active and inactive subscribers. Without reliable engagement signals, marketers can often continue sending to users who have not interacted for months. Inbox providers prioritise meaningful engagement over list size, so sending to dormant users accelerates the decline in domain reputation. A weakened domain reputation affects whether emails land in the primary inbox, the promotions tab, spam or are quietly suppressed.
Even highly relevant and well-targeted messages may fail to reach recipients because the domain has been deemed low trust. In severe cases, poor domain reputation can spill over into operational emails such as password resets, confirmations or important account notifications, creating risk across the organisation.
Once domain reputation declines, recovery is slow and requires sustained, controlled sending to the most engaged users. During this period, visibility drops, engagement deteriorates further, and the cost of acquisition rises as email becomes less effective at retaining and nurturing customers. So while protecting list size may feel important, keeping data clean to help protect domain reputation is what keeps email viable in the long run.
In summary, the decline in email engagement is hardly ever down to just one cause, but usually a mix of issues that gradually erode the effectiveness of even well-established programs. Understanding these root causes is the first step toward turning things around. By identifying where these breakdowns occur, you can begin to address them with targeted strategies.
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