Can spam filters trigger email unsubscribes and how to prevent it?
Summary
What email marketers say10Marketer opinions
Email marketer from Litmus responds to the issue of bots clicking links. One of their solutions involves adding a honeypot link (a link invisible to humans) to your emails; bots will often click these links, and you can then filter out these bots from your data.
Email marketer from Mailjet explains that you can add authentication to the unsubscribe process, such as requiring users to log in or verify their email address before completing the unsubscription. This prevents unauthorized unsubscribes by bots.
Email marketer from WebmasterWorld forum mentions they use a honeypot technique where they have a hidden field that, if populated, indicates a bot submission. This allows them to filter out bot-triggered unsubscribe requests.
Marketer from Email Geeks shares that Gmail offers the ability to unsubscribe when a message is marked as spam, dependent on the list-unsubscribe header, and suggests other providers might do something similar.
Email marketer from DigitalPoint forum explains the need for a confirmed opt-out process. The user has to actually click the link that confirms the unsubscription. Helps prevent false unsubscribes.
Email marketer from Reddit suggests adding a delay to the unsubscribe process. Don't remove the user immediately, rather add a task to a queue that runs a minute later.
Email marketer from SendGrid explains that they advise using a double opt-in process to ensure that subscribers genuinely want to receive emails. This helps prevent bots and spam filters from triggering subscriptions, which can lead to unwanted unsubscribes later on.
Email marketer from StackOverflow suggests logging the IP address of the user when they unsubscribe. If there is a surge of unsubscribes from one IP, then this will help identify if it is a bot or spam filter that is causing it.
Email marketer from Neil Patel's Blog explains that spam filters can sometimes trigger unsubscribes if they follow links in the email to check their validity, which can unintentionally trigger the unsubscribe link. To prevent this, implement a double opt-in process for subscriptions and use a confirmed opt-out process for unsubscribes, requiring an extra step to confirm the unsubscription.
Email marketer from Email on Acid shares that spam filters clicking links and triggering unsubscribes is a known issue. Their recommendation is to implement a CAPTCHA or similar challenge on the unsubscribe page to prevent automated systems from completing the unsubscription process.
What the experts say5Expert opinions
Expert from Word to the Wise recommends implementing a CAPTCHA before the unsubscribe action is completed, to prevent bots or automated systems from unsubscribing users unintentionally.
Expert from Email Geeks shares their experience with spam filters causing unsubscribes and inflated clicks, noting it's an industry-wide issue. They now require an extra click for unsubscription.
Expert from Email Geeks, Laura Atkins, explains that POST is used to post a change and GET is used to read data. Alexander Zeh adds that GET should never alter data on the server, while POST is supposed to change something.
Expert from Email Geeks recommends changing "one click" unsubscribe to "two click" unsubscribe, regardless of method, and suggests that list-unsub should require POST for immediate unsubscribe.
Expert from Email Geeks initially explains that an unsubscribe link should not complete the unsubscribe if the link is followed, but then corrects themselves.
What the documentation says4Technical articles
Documentation from datatracker.ietf.org explains that RFC 8058 defines a method for one-click unsubscribe via the List-Unsubscribe header, but also acknowledges the potential for abuse by automated systems. The RFC suggests implementations should consider rate-limiting and confirmation steps to mitigate unintended unsubscribes.
Documentation from Google explains that high spam complaint rates can negatively impact deliverability. Although it doesn't directly address bot-triggered unsubscribes, it highlights the importance of maintaining a clean list and providing easy, legitimate unsubscribe options to reduce spam complaints, which indirectly addresses the issue.
Documentation from RFC 2369 defines the List-Unsubscribe header, explaining how it enables users to easily unsubscribe from mailing lists. While it doesn't directly address spam filter unsubscribes, it's fundamental to understanding the mechanisms that can be unintentionally triggered by filters.
Documentation from Mailchimp explains that using reCAPTCHA on signup forms can prevent bots from subscribing to your email list, which can help to reduce spam filter interactions with your unsubscribe links later. They recommend this as a best practice for list hygiene.