Can spam filters trigger email unsubscribes and how to prevent it?
Michael Ko
Co-founder & CEO, Suped
Published 19 May 2025
Updated 16 Aug 2025
7 min read
It’s a peculiar and frustrating scenario, but yes, spam filters can inadvertently trigger email unsubscribes. This often happens not because a human recipient clicked an unsubscribe link, but due to automated processes designed to vet incoming emails. These automated clicks can lead to unexpected list churn and inaccurate engagement metrics, making it difficult to gauge the true health of your email program.
The core of the issue lies in how some security systems and mailbox providers scan emails for malicious content or to pre-render messages. During this scanning process, these systems might follow every link within an email, including the unsubscribe link. If your unsubscribe mechanism is set up for a one-click unsubscribe via a GET request, these automated clicks can process as legitimate unsubscribe requests, even without human intent.
Understanding this behavior is crucial for maintaining accurate subscriber lists and ensuring your email deliverability remains strong. We'll explore why these automated unsubscribes happen and, more importantly, how you can implement strategies to prevent them.
Why spam filters click unsubscribe links
Automated email security systems and spam filters employ various techniques to protect users from phishing attempts, malware, and unwanted commercial messages. One common practice is link pre-fetching or scanning. This involves the filter following all links in an email to analyze their content and destination before the email even reaches the recipient's inbox. The goal is to identify and neutralize threats before they can harm the user.
When an email's unsubscribe link is a simple GET request that immediately processes the unsubscribe, these automated systems can inadvertently trigger it. The filter doesn't know the difference between a human click and an automated scan, leading to a legitimate unsubscribe event recorded by your email service provider (ESP).
This also applies to the List-Unsubscribe header. If this header contains a mailto: address or a URL that accepts a GET request for unsubscribing, it's susceptible to automated processing by filters like those at Gmail. This can lead to what appears to be a false unsubscribe from the recipient's perspective, as they never intentionally opted out.
Impact on deliverability and sender reputation
The impact of these automated unsubscribes extends beyond just losing subscribers. They can skew your engagement metrics, making it harder to accurately assess campaign performance. Inflated click rates also emerge, as these automated scans register as legitimate interactions, further muddying your data. Over time, a high rate of unintentional unsubscribes can also negatively affect your sender reputation, as ESPs might interpret it as a sign that your emails are not truly wanted by the recipients.
A damaged sender reputation can lead to more of your emails landing in the spam folder or even being blocked entirely. This is why it's vital to address the root causes of these automated unsubscribes and implement robust solutions to protect your email program.
Compliance with regulations like the CAN-SPAM Act also mandates easy unsubscribe options. While this is important for user experience and legal compliance, it also means your unsubscribe mechanism must be resilient enough to handle automated interactions without causing unintended subscriber loss. Balancing compliance with protection against bot-triggered unsubscribes is a key challenge for email marketers.
Preventative measures for false unsubscribes
The primary way to combat automated unsubscribes is to implement a two-click unsubscribe process or ensure your unsubscribe links use a POST request rather than a GET request for confirmation. A two-click process typically directs the user to a landing page where they must confirm their unsubscribe request. This extra step acts as a barrier to automated bots, ensuring only human users can complete the unsubscribe.
For the List-Unsubscribe header, implementing RFC 8058 is the recommended solution. This RFC specifies how to signal a one-click unsubscribe functionality that requires a POST request. By requiring a POST request, you prevent filters from automatically unsubscribing users with a simple link click.
Here's an example of how to implement the List-Unsubscribe header with POST support, ensuring that automated systems are less likely to trigger unintended unsubscribes while still providing the required one-click option for compliant email clients.
This setup allows email clients that support RFC 8058 to perform a POST request for the one-click unsubscribe, which is safer against bot clicks. For older clients, the mailto link remains available.
Best practices for email list hygiene
Beyond technical implementations, several best practices can further protect your email program from unintended unsubscribes and ensure robust email deliverability. Maintaining a clean email list is paramount. Regularly remove inactive subscribers and hard bounces to prevent engagement issues that could trigger spam filters.
Monitoring your engagement metrics, including open rates, click-through rates, and unsubscribe rates, can help identify unusual patterns. Sudden spikes in unsubscribes or clicks without corresponding human activity might indicate automated filter interactions. Utilize tools like Outlook's or Gmail'sPostmaster Tools to gain insights into how your emails are performing and being categorized.
Finally, focus on providing valuable content that your subscribers genuinely want to receive. High-quality, relevant emails reduce the likelihood of manual spam complaints, which can also trigger automated filtering and impact your sender reputation. A healthy list with engaged subscribers is your best defense against both human and automated unsubscribe actions.
Ensuring genuine unsubscribes
Understanding and addressing the phenomenon of spam filters triggering email unsubscribes is crucial for any sender. While automated systems are designed to protect users, they can inadvertently impact your legitimate email marketing efforts. By implementing two-step unsubscribe processes, adhering to RFC 8058 for List-Unsubscribe headers, and maintaining rigorous list hygiene, you can significantly mitigate the risk of these false unsubscribes.
Proactive monitoring of your email metrics and adapting your unsubscribe mechanisms are key steps. These measures not only protect your subscriber base but also reinforce your sender reputation and ensure your messages reach their intended audience. Prioritizing these technical and strategic approaches will help you navigate the complexities of email deliverability effectively.
Views from the trenches
Best practices
Implement a two-click unsubscribe process for web-based links to prevent automated bot unsubscriptions.
Use the `List-Unsubscribe-Post` header with a POST request to comply with RFC 8058, safeguarding against auto-unsubscribes.
Regularly monitor your email engagement data for unusual click or unsubscribe spikes, which may indicate bot activity.
Maintain clean email lists by promptly removing unengaged subscribers and bounced addresses to improve reputation.
Common pitfalls
Using GET requests for unsubscribe links allows spam filters to inadvertently trigger unsubscribes through automated scans.
Ignoring inflated click-through rates caused by security filters can lead to inaccurate campaign performance analysis.
Failing to implement RFC 8058 for List-Unsubscribe headers can result in unexpected subscriber loss from automated systems.
Not regularly cleaning your email lists can lead to higher bounce rates and decreased sender reputation, increasing filter scrutiny.
Expert tips
Always verify the IP addresses associated with sudden, high-volume clicks or unsubscribes to identify potential bot activity.
Ensure your email service provider (ESP) supports and properly implements RFC 8058 for List-Unsubscribe functionality.
Consider segmenting your audience and tailoring content to improve engagement, naturally reducing spam complaints and unsubscribes.
Educate your subscribers on how to whitelist your email address to ensure consistent delivery past aggressive filters.
Marketer view
Marketer from Email Geeks says that Gmail offers the ability to unsubscribe when a message is marked as spam, often dependent on the List-Unsubscribe header. Other providers might do similar actions.
2022-02-23 - Email Geeks
Marketer view
Marketer from Email Geeks says that automated actions are highly indicative of some endpoint security system, and suggested checking the IP address of the clicks.
Gmail. This can lead to what appears to be a false unsubscribe from the recipient's perspective, as they never intentionally opted out.
Outlook's or 
Gmail'sPostmaster Tools to gain insights into how your emails are performing and being categorized.
