Summary
Subscribers are automatically unsubscribed without their knowledge due to a confluence of technical, behavioral, and infrastructural factors. Microsoft O365, aggressive spam filters, graymail filters, and security software often take actions that the user hasn't initiated. Technical causes include improperly implemented one-click unsubscribe features, filters following links, especially using GET requests which are triggered by bots, broken unsubscribe links, and PII exposure. Behavioral aspects involve recipients marking emails as spam (triggering feedback loops and EOP actions) when they lack preference management options or receive transactional emails after unsubscribing from marketing lists. Poor list hygiene (failure to remove inactive addresses) and a negative shared IP reputation further contribute to automatic unsubscriptions. Properly aligning email authentication, regular list cleaning, careful unsubscribe link implementation (avoiding GET), monitoring complaint rates, and providing preference centers are key to mitigating these issues.
Key findings
- Microsoft O365 & Filters: Microsoft O365, aggressive spam filters, and graymail filters automatically unsubscribe users.
- One-Click & GET: Improperly implemented one-click unsubscribe and using HTTP GET requests in unsubscribe links trigger unwanted actions.
- Broken Links & Security: Broken unsubscribe links and security software can automatically trigger unsubscriptions.
- Spam Marking & FBLs: Recipients marking emails as spam triggers feedback loops and automated unsubscriptions.
- Poor Hygiene & Shared IPs: Poor list hygiene and negative shared IP reputation lead to automatic unsubscriptions.
- Preference Centers: Lack of preference centers leads to users marking email as spam.
Key considerations
- Authentication Alignment: Ensure proper SPF, DKIM, and DMARC authentication.
- List Hygiene Practices: Regularly clean your email lists, removing inactive or bounced addresses.
- Unsubscribe Link Implementation: Carefully implement unsubscribe links, avoiding HTTP GET requests and ensuring proper functionality.
- Feedback Loop Management: Monitor and manage feedback loops to address spam complaints promptly.
- Provide Preference Options: Offer subscribers a preference center to manage their subscriptions.
- Dedicated IPs: Consider using a dedicated IP address to manage your sender reputation.
- Address PII: Avoid putting the email address in the URL when using HTTP GET.
- Monitor Complaint Rates: Monitor and proactively address causes for spam complaints.
What email marketers say
12 marketer opinions
Subscribers may be automatically unsubscribed without their knowledge due to a variety of factors. These include aggressive spam filters unsubscribing based on triggers, recipients marking emails as spam, and poor list hygiene practices leading ESPs to automatically unsubscribe recipients. Issues related to unsubscribe links, like using GET requests or broken links, also contribute. Additionally, shared IP addresses, aggressive spam filters or graymail filters, or even security software can trigger unintended unsubscribes. Microsoft O365 may also initiate unsubscribes. Furthermore, not providing clear email preference options may cause users to mark emails as spam, leading to automatic unsubscriptions. Properly aligning email authentication is key to avoiding these issues. Regularly cleaning email lists and ensuring proper GET/POST use is critical as well.
Key opinions
- Microsoft O365: Microsoft O365 may automatically unsubscribe recipients, especially if authentication isn't properly aligned.
- GET Requests: Using GET requests in unsubscribe links can cause unintended unsubscribes due to bot activity and privacy concerns.
- List Hygiene: Poor list hygiene, such as not removing inactive addresses, leads ESPs to automatically unsubscribe recipients.
- Complaint Rate: A high complaint rate prompts ESPs to automatically unsubscribe users to protect their reputation.
- Spam Filters: Aggressive spam filters may automatically unsubscribe users based on keyword detection or sender reputation.
- Broken Links: Broken or incorrect unsubscribe links can lead email clients to automatically unsubscribe users.
- Security Software: Security software may automatically click unsubscribe links, causing unintended unsubscribes.
- Preference Centers: Lack of clear email preference options may cause users to mark emails as spam, triggering automatic unsubscriptions.
- Shared IP: Using a shared IP address with a poor reputation can cause ESPs to automatically unsubscribe recipients.
Key considerations
- Authentication: Ensure proper email authentication (SPF, DKIM, DMARC) to improve deliverability and prevent unintended unsubscribes.
- List Management: Regularly clean your email list to remove inactive, bounced, and unengaged subscribers.
- Unsubscribe Process: Implement a clear and easy unsubscribe process, avoiding GET requests and ensuring links are functional.
- Preference Centers: Provide subscribers with a preference center to manage their email subscriptions.
- Monitor Complaints: Monitor complaint rates and address any issues to maintain a positive sender reputation.
- Dedicated IP: Consider using a dedicated IP address to control your sending reputation.
Marketer view
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.
1 Mar 2022 - Email Geeks
Marketer view
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.
2 Aug 2023 - Email Marketing Forum
What the experts say
6 expert opinions
Automatic, unknown unsubscriptions stem from filtering systems following unsubscribe links, especially with one-click unsubscribe and HTTP GET requests. Feedback loops (FBLs), where marking emails as spam triggers automated unsubscriptions to prevent further complaints, also contribute. Graymail filtering, identifying emails users no longer want and unsubscribing them automatically, is another factor. Providers also unsubscribe users flagged for sending abusive emails to protect their customers.
Key opinions
- Filtering Systems: Filters follow unsubscribe links, causing unintended unsubscriptions.
- One-Click Unsubscribe: One-click unsubscribe, while convenient, increases the risk of non-human clicks causing unsubscriptions.
- HTTP GET: Improper HTTP GET implementation in unsubscribe links triggers automated unsubscribes.
- Feedback Loops (FBLs): Marking emails as spam triggers automated unsubscriptions through FBLs.
- Graymail Filtering: Systems automatically unsubscribe users from graymail lists (emails no longer wanted).
- Abuse Reporting: Mail providers automatically unsubscribe users flagged for sending abusive or spam emails.
Key considerations
- Monitor Filtering: Be aware of how filtering systems might interact with unsubscribe links.
- Avoid One-Click: Carefully consider the use of one-click unsubscribe due to potential for unintended clicks.
- Implement HTTP Correctly: Ensure proper implementation of HTTP GET/POST methods in unsubscribe links.
- Manage FBLs: Monitor feedback loops and address spam complaints promptly.
- Segment Graymail: Implement strategies for segmenting and engaging graymail recipients before they unsubscribe.
- Prevent Abuse: Adhere to email best practices to avoid being flagged for sending abusive or spam emails.
Expert view
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).
17 Oct 2022 - Email Geeks
Expert view
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.
7 Jan 2023 - Spam Resource
What the documentation says
4 technical articles
Subscribers are automatically unsubscribed without their knowledge due to several documented reasons. Google Support highlights that improper implementation of one-click unsubscribe in Gmail can lead to filters or Gmail initiating the unsubscribe. The RFC Editor notes that using HTTP URLs with GET requests in the List-Unsubscribe header improperly can cause bots to trigger unintended unsubscribes. Microsoft explains that Exchange Online Protection (EOP) may automatically unsubscribe recipients with high complaint volumes. Mailchimp points out that if a recipient unsubscribes from a marketing list but still receives transactional emails, they may report them as spam, triggering automated unsubscriptions from all lists.
Key findings
- Gmail One-Click: Improper one-click unsubscribe implementation can lead to automatic unsubscriptions by Gmail.
- HTTP GET: Using HTTP GET requests in List-Unsubscribe headers improperly can cause unintended bot-triggered unsubscriptions.
- Exchange Online Protection (EOP): EOP may automatically unsubscribe recipients with high complaint volumes to protect users.
- Transactional Emails: Sending transactional emails to users unsubscribed from marketing lists can trigger spam reports and automated unsubscriptions from all lists in Mailchimp.
Key considerations
- One-Click Implementation: Properly implement Gmail's one-click unsubscribe feature.
- Unsubscribe Method: Avoid using HTTP GET requests in List-Unsubscribe headers; prefer POST requests.
- Complaint Monitoring: Monitor complaint rates and address negative signals to prevent automatic unsubscriptions by EOP.
- List Segmentation: Segment marketing and transactional email lists to avoid sending unwanted emails to unsubscribed users.
Technical article
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.
14 Feb 2025 - Google Support
Technical article
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.
10 Dec 2024 - RFC Editor
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