Summary
Email engagement rates are declining due to the combined effects of enhanced List-Unsubscribe header behavior and subscriber choices within segmented email preference centers. The one-click functionality of the List-Unsubscribe header, a key deliverability best practice, allows for swift removal of disengaged recipients, leading to a smaller overall active mailing list. Simultaneously, mailbox providers increasingly expect a broad, often global, suppression from all non-transactional mail following a List-Unsubscribe action; failure to meet this expectation results in spam complaints and reduced inbox placement. Furthermore, when presented with detailed preference centers, subscribers frequently opt to receive less frequent emails or narrow their content choices. While these factors contribute to a decrease in aggregate engagement metrics, they often signify a healthier, more active subscriber base and improved list hygiene, ultimately benefiting long-term deliverability.
Key findings
- Rapid Unsubscribe: The efficiency of the List-Unsubscribe header, particularly its one-click implementation, facilitates the swift removal of even passively disengaged subscribers, naturally shrinking the total active list size and lowering overall engagement figures.
- Broad Suppression Expectation: Mailbox providers, notably Gmail, expect List-Unsubscribe actions to result in a broad, often global, suppression from non-transactional mail; failure to honor this leads to user frustration, spam complaints, and diminished deliverability.
- Reduced Email Volume: Segmented email preference centers empower subscribers to choose fewer emails or narrow their content interests, which directly translates to fewer opportunities for engagement and a decrease in overall engagement volume from those specific segments.
- User Expectation vs. Functionality Disconnect: When a subscriber expects a global unsubscribe via an in-app or List-Unsubscribe option but only a single preference is actioned, they are likely to mark subsequent emails as spam, signaling to mailbox providers that their opt-out was not honored.
- List Hygiene Improvement: An apparent drop in total engagement metrics often indicates more efficient list cleansing and a healthier, more active subscriber base, improving per-email engagement rates for the remaining, truly interested audience and enhancing long-term deliverability.
Key considerations
- Honor Broad Unsubscribes: Implement List-Unsubscribe mechanisms that align with mailbox provider expectations for broad suppression from non-transactional emails to avoid spam complaints and maintain sender reputation.
- Verify Functionality and Technical Setup: Regularly verify the functionality of List-Unsubscribe endpoints and use unique List-ID headers or sender identities for distinct mailing lists to prevent confusion and ensure proper unsubscribe handling.
- Optimize Preference Centers: Design clear and manageable email preference centers that empower subscribers to tailor their content and frequency without overwhelming them, while also clearly communicating the scope of their unsubscribe choices.
- Acknowledge Shift in Metrics: Recognize that lower aggregate engagement numbers might reflect a healthier, higher quality, and more engaged audience rather than a true decline in program effectiveness, as disengaged subscribers are efficiently removed.
- Maintain Traditional Unsubscribe Links: Always include a clearly visible traditional unsubscribe link within email bodies to ensure CAN-SPAM compliance and provide a straightforward, often broader, opt-out method for recipients.
What email marketers say
13 marketer opinions
Expanding on the dynamics affecting email engagement, the combined influence of refined List-Unsubscribe header functionality and explicit subscriber choices within preference centers contributes to a nuanced decline in overall engagement rates. The ease of one-click unsubscribing via the List-Unsubscribe header efficiently prunes mailing lists of less engaged recipients, thereby reducing the total number of potential interactions. This efficiency, while improving list hygiene, can naturally lower aggregate engagement metrics. Simultaneously, mailbox providers increasingly expect a broad, even global, cessation of non-transactional mail following a List-Unsubscribe request, and non-compliance is often flagged, resulting in more spam complaints and diminished inbox placement. Furthermore, when subscribers engage with preference centers, they frequently opt to receive fewer emails or highly specialized content, directly limiting the volume of messages sent and consequently, the total opportunities for engagement. This shift, driven by both technical efficiencies and user preferences, leads to a healthier, albeit smaller, engaged audience, reshaping how engagement is measured.
Key opinions
- Efficient Subscriber Pruning: The streamlined nature of the List-Unsubscribe header, particularly one-click options, rapidly removes passively interested subscribers, leading to a smaller pool of recipients and a consequent decrease in total engagement numbers.
- Misalignment of Unsubscribe Scope: When senders fail to honor the mailbox provider expectation of a broad, global unsubscribe from non-transactional mail following a List-Unsubscribe action, it leads to increased spam complaints and a perceived lack of 'honoring unsubscribes,' negatively impacting inbox placement and engagement.
- Subscriber-Initiated Volume Reduction: Offering segmented email preferences often results in subscribers actively choosing to receive fewer emails or narrower content categories, which directly limits the total volume of emails they receive and thus reduces their overall engagement opportunities.
- Complex Preference Center Frustration: Overly intricate or confusing preference centers can overwhelm subscribers, prompting them to choose the simplest option-receiving fewer emails or complete unsubscribes, rather than granular adjustments, leading to a net decrease in engagement.
- Indicator of Healthier List: A reduction in aggregate engagement figures, while seemingly negative, often signifies an improvement in list hygiene and a more active, higher-quality subscriber base, as disengaged recipients are efficiently filtered out.
Key considerations
- Prioritize Comprehensive Unsubscribe Handling: It's crucial for marketers to implement List-Unsubscribe mechanisms that ensure a broad, non-transactional suppression aligned with mailbox provider expectations, mitigating spam complaints and reputation damage.
- Ensure Technical Accuracy for List-Unsubscribe: Marketers must regularly verify the functionality and correct technical setup of their List-Unsubscribe endpoints, including using unique List-ID headers for distinct campaigns, to guarantee proper and effective opt-out processing.
- Streamline Preference Center Experience: Designing user-friendly and clear email preference centers is vital to allow subscribers to easily customize their email frequency and content, preventing frustration that could lead to full unsubscribes.
- Re-evaluate Engagement Metrics Holistically: Marketers should interpret shifts in aggregate engagement rates with an understanding that lower total numbers may reflect a healthier, more actively engaged audience, rather than a decline in program performance.
- Reinforce Unsubscribe Compliance with Traditional Links: Beyond List-Unsubscribe, consistently including a clearly visible traditional unsubscribe link within email bodies remains essential for CAN-SPAM compliance and to offer a robust, unambiguous opt-out path.
Marketer view
Marketer from Email Geeks explains that Gmail's "not honoring unsubscribes" flag often means receiving spam complaints, leading to decreased engagement due to increased spam folder placement. She also notes that not including unsubscribe links on emails, even transactional ones, can contribute to this issue, as Gmail interprets the warning as a sign of spam complaints.
28 Jul 2023 - Email Geeks
Marketer view
Marketer from Email Geeks emphasizes that continuing to send email to recipients who have unsubscribed will lead to problems. He explains that the scope of an 8058 unsubscribe (List-Unsubscribe) is flexible, and senders should consider broader suppression from all non-transactional mail, especially if Gmail's observation suggests complaints after unsubscribes. He also advises verifying the functionality of the 8058 unsubscribe endpoint. Later, he adds that the in-app unsubscribe expectation is for a broad effect, removing recipients from all non-essential communication, even if they signed up for multiple lists, unless explicitly distinct categories. He confirms that the issue is not complying with mailbox providers' expectations regarding not sending unwanted mail.
25 Sep 2024 - Email Geeks
What the experts say
4 expert opinions
The observed decline in email engagement rates is a multifaceted issue stemming from both the enhanced functionality of the List-Unsubscribe header and how subscribers manage their preferences within segmented options. The widespread adoption of one-click unsubscribe via the List-Unsubscribe header efficiently removes less engaged subscribers, which, while beneficial for list health, naturally lowers overall engagement statistics. A critical challenge arises when there is a disconnect between a subscriber's expectation of a global unsubscribe and the system's execution of only a partial or segment-specific opt-out. Such discrepancies, alongside delays in processing unsubscribe requests, often prompt users to mark subsequent emails as spam, signaling to mailbox providers that their opt-out was not fully honored. Ultimately, this leads to a more refined and engaged email list, with engagement metrics more accurately reflecting the activity of genuinely interested recipients, thus improving long-term deliverability even if raw numbers seem to fall.
Key opinions
- One-Click Impact: The streamlined nature of the List-Unsubscribe header, particularly one-click functionality, leads to a higher volume of immediate unsubscribes, which can reduce aggregate engagement metrics but ultimately results in a more qualified subscriber base.
- Unsubscribe Expectation Gap: A fundamental mismatch between a subscriber's expectation of a global unsubscribe and a system that only unsubscribes them from a single list or segment frequently results in further spam complaints after initial opt-out attempts.
- Delayed Suppression Signals: Mailbox provider warnings, like Gmail's, indicate that an unsubscribe request was not honored promptly (e.g., within 48 hours), potentially due to new list uploads overriding suppressions or misconfigured sending sources, leading to user frustration and spam reports.
- Benefits of List Cleansing: Despite a perceived drop in overall engagement numbers, the efficient removal of disengaged subscribers through simpler unsubscribe processes significantly benefits sender reputation and long-term deliverability by ensuring that engagement metrics reflect a genuinely active audience.
- Authentic Engagement Metrics: While aggregate engagement figures may decrease, this shift actually provides more accurate engagement metrics by focusing on the interactions of truly interested subscribers, as unengaged contacts are efficiently filtered out.
Key considerations
- Fulfill Global Unsubscribes: Marketers must ensure their unsubscribe processes, including List-Unsubscribe headers, honor the user's implicit expectation of a global opt-out from all non-transactional mail, rather than only from specific segments, to prevent subsequent spam complaints.
- Promptly Process Requests: It is critical to process all unsubscribe requests, especially those initiated via List-Unsubscribe, within the required timeframe, such as Gmail's 48-hour window, to avoid sender reputation damage indicated by warning messages.
- Audit Unsubscribe Paths: Regularly audit and verify all unsubscribe mechanisms-List-Unsubscribe, preference centers, and in-email links-to confirm they function correctly and suppress recipients across all relevant lists to align with user expectations.
- Reframe Engagement Metrics: Marketers should view increased unsubscribe rates, facilitated by easier one-click options, not as a sign of declining engagement but as an indication of healthier list hygiene and a more focused, truly interested audience.
- Clarify Opt-Out Scope: Within preference centers, clearly communicate the scope of unsubscribe options, distinguishing between global opt-outs and specific content preferences, to manage subscriber expectations and reduce frustration that leads to spam complaints.
Expert view
Expert from Email Geeks states that the Gmail warning means a user asked to be unsubscribed within 48 hours and wasn't, proposing theories like new list uploads overriding unsubs or sending from other sources.
3 Oct 2023 - Email Geeks
Expert view
Expert from Email Geeks highlights the disconnect between user expectation and unsubscribe functionality. If a subscriber expects a global unsubscribe but only a single preference is actioned, they are likely to mark subsequent emails as spam, leading Gmail to observe an unsubscribe click followed by a spam complaint.
5 Oct 2022 - Email Geeks
What the documentation says
6 technical articles
The decline in email engagement rates is largely attributable to the evolving behavior of the List-Unsubscribe header and subscriber choices through preference centers. The one-click functionality of the List-Unsubscribe header simplifies opting out, leading to faster list churn as passively or fully disengaged subscribers quickly exit. This efficiency, while beneficial for list hygiene, naturally reduces the total active subscriber base and, consequently, overall aggregate engagement metrics. Mailbox providers, such as Google, actively leverage this header, sometimes automatically unsubscribing users who consistently ignore emails, further refining mailing lists. Concurrently, preference centers allow subscribers to customize their email frequency and content, often resulting in choices for fewer emails. This reduction in email volume inherently limits the opportunities for opens and clicks, contributing to the overall decrease in engagement. While raw engagement numbers may appear lower, these dynamics ultimately cultivate a healthier, more active subscriber list, ensuring engagement metrics more accurately reflect the interactions of genuinely interested recipients.
Key findings
- Simplified Opt-Out Reduces List Size: The ease of one-click List-Unsubscribe leads to faster removal of disengaged subscribers, shrinking the active mailing list and lowering total engagement.
- ISP-Driven List Culling: Mailbox providers actively use the List-Unsubscribe header, potentially auto-unsubscribing inactive users, which refines the list but decreases the overall pool of potential engagers.
- Preference Centers Limit Engagement Opportunities: When subscribers use preference centers to receive fewer emails or highly specific content, it directly reduces the volume of messages sent to them, thereby limiting opportunities for opens and clicks.
- Lower Total Engagement, Healthier List: Although overall engagement numbers may decrease due to these mechanisms, the resulting list is healthier, composed of truly active subscribers, which can lead to higher per-email engagement rates and improved deliverability.
- Impact on Overall Metrics: The combined effect of efficient unsubscribe processes and subscriber-driven volume reductions results in a genuine decrease in aggregate engagement metrics, even if per-subscriber engagement remains strong.
Key considerations
- Embrace Enhanced Unsubscribe Methods: Acknowledge and fully implement the List-Unsubscribe header, including one-click functionality, as a critical best practice for deliverability, even if it leads to higher unsubscribe rates and lower aggregate engagement.
- Rethink Engagement Metrics: Shift focus from raw total opens and clicks to per-email engagement rates and overall list health, understanding that lower aggregate numbers often reflect a more refined, genuinely active subscriber base.
- Optimize Preference Centers: Design user-friendly preference centers that empower subscribers to manage their email frequency and content, recognizing that this will likely lead to some opting for fewer emails and thus fewer engagement opportunities.
- Align with ISP Expectations: Understand that mailbox providers actively use the List-Unsubscribe header for list culling, sometimes automatically unsubscribing inactive users; align your list management and suppression processes accordingly.
Technical article
Documentation from IETF explains that RFC 8058's introduction of one-click List-Unsubscribe significantly simplifies the unsubscribe process, leading to more frequent and quicker departures of subscribers, including those who were passively disengaged, which naturally reduces the total active list size and consequently, overall engagement figures.
23 Feb 2025 - IETF
Technical article
Documentation from AWeber Blog outlines that while preference centers empower subscribers to tailor content and frequency, this often results in users opting for fewer emails. Receiving less email inherently means fewer opportunities for opens and clicks, leading to a decrease in overall engagement volume from those specific subscribers.
22 Jul 2024 - AWeber Blog
How does the List-Unsubscribe header affect email deliverability with a preference center?
Why are email clicks, conversions and unsubscribes declining despite high deliverability?
Why are List-Unsubscribe requests from Gmail increasing suddenly?
Why are we seeing abnormally high opt-out rates in email campaigns?
Why did one-click unsubscribe disappear, and open rates drop after implementing Gmail and Yahoo requirements?
Why have email engagement rates dropped significantly for large broadcast sends since February?
