Why are subscribers automatically unsubscribing without their knowledge?

Marketer from Email Geeks warns to beware of the fact that many/sometimes unsubscribe links that work with HTTP GET requests, put the plain text email address in the URL parameters. This then gets picked up by various analytics/tracking systems and of course is PII, which likely violates certain consumer rights and vendor agreements. If ever you see an email address in the URL, it’s a slippery slope, at least for European audiences.

Email marketer from Email Marketing Forum explains that if using a shared IP address, the sending reputation can be affected by other users. If the shared IP is flagged for spam, it can cause ESPs to automatically unsubscribe recipients from emails sent using that IP, even if the sender is following best practices.

Email marketer from StackExchange shares that some security software or browser extensions might automatically click unsubscribe links as a security measure, without the user's explicit consent. This prevents potential phishing or malicious content from being delivered.

Marketer from Email Geeks says they also saw those GET requests from Microsoft IPs, for emails sent to Office365 mailboxes.

Email marketer from ActiveCampaign shares that if subscribers are not given clear options to manage their email preferences (via a preference center), they may simply mark emails as spam to stop receiving them. This can lead to automatic unsubscribes triggered by the ESP.

Email marketer from NeilPatel.com shares that sometimes subscribers are automatically unsubscribed if a list isn't regularly cleaned. Inactive subscribers, or those who haven't engaged recently, might be removed to maintain list health and improve deliverability, and these users may not realize they were unsubscribed.

Marketer from Email Geeks shares they have seen Microsoft do this - as in recipients using O365 where the recipients have no knowledge of the unsubscribe and aligning authentication usually fixes it.

Email marketer from Sendinblue answers that a high complaint rate can lead ESPs to automatically unsubscribe users to protect their reputation. Subscribers who mark emails as spam are essentially unsubscribing themselves without knowing the full implications.

Email marketer from Email on Acid answers that if the unsubscribe link is broken or directs to an error page, some email clients may interpret this as a request to unsubscribe and do so automatically to improve user experience.

Marketer from Email Geeks explains the technical difference between a GET and POST is that a GET request is encoded as part of the URL while a POST request is encapsulated in the HTTP request. So any single-action URL (such as a list-unsubscribe link) has to be a GET because it's only a single link and all of the info has to be there. However, what happens when the call is made (update a table, unsubscribe an address) is completely up to the programmer. POST is usually a better choice chiefly because the data can be protected by SSL and is not publicly visible in the URL. Most web forms use POST. However, because you can't encode a POST within a URL, GET has its place too.

Email marketer from Litmus shares that poor list hygiene practices, such as not regularly removing bounced or inactive addresses, can lead to ESPs automatically unsubscribing recipients. ESPs do this to protect their own reputation and deliverability rates.

Email marketer from Reddit shares that some aggressive spam filters might automatically unsubscribe users based on certain triggers, like keyword detection or sender reputation. These unsubscribes happen server-side, without the recipient's direct action.

Expert from Email Geeks explains if clicking on that link creates an automatic unsubscribe in your system, then, yes, it will. the Get/Post thing is something in http. as i understand it (and my understanding is shakey at best) one of those types of http calls immediately changes the underlying data and has an effect (so if any URL checker follows the link the address is immediately unsubscribed from the mail) the other type of http call does not immediately change the server data, so simply following the link does not result in the underlying data (so when a URL checker follows the link the address is not unsubscribed from the mail).

Expert from Spam Resource explains that feedback loops (FBLs) can cause automatic unsubscribes. If recipients mark emails as spam, this information is sent back to the sender through the FBL. Some email systems are configured to automatically unsubscribe recipients who trigger the FBL to prevent further spam complaints.

Expert from Email Geeks explains this is one of the reasons they do not recommend one-click unsubscribe - non-human clicks that end up unsubscribing.

Expert from Word to the Wise (Laura Atkins) explains that some filtering systems identify 'graymail' (emails that users may have opted into but no longer want) and automatically unsubscribe users from these lists. This can happen without the user explicitly requesting to unsubscribe.

Expert from Spam Resource explains that, when users mark a message as abusive or spam, some mail providers use this information to automatically unsubscribe the user to prevent further abusive emails from being sent to that user. This is one way to protect their customer base from unwanted communications.

Expert from Email Geeks suggests that it’s very likely that the subscribers are all customers of one filtering system or another and the filters are following all the links in your emails.

Documentation from Google Support explains that Gmail supports one-click unsubscribe, where users can unsubscribe directly from the Gmail interface. If a sender doesn't properly implement this, filters or Gmail itself might initiate the unsubscribe process on behalf of the user.

Documentation from RFC Editor explains that the List-Unsubscribe header can be implemented with either a mailto: or an HTTP URL. If using HTTP, improper configuration, like using a GET request that automatically unsubscribes upon being crawled by a bot, can cause unintended unsubscribes.

Documentation from Microsoft explains that Exchange Online Protection (EOP) may automatically unsubscribe recipients from mailing lists if it detects a high volume of complaints or other negative signals. This is done to protect users from unwanted emails.

Documentation from Mailchimp explains that if a recipient is unsubscribed from a marketing list but still receives transactional emails, they might report the emails as spam. This can trigger automated unsubscribes from all lists, even if the recipient intended to only unsubscribe from the marketing list.