Summary
Email providers and security vendors frequently employ automated link testing mechanisms, a process designed to scan emails for malicious content and verify URLs before delivery. This practice, utilized by major players such as Oath (Yahoo, AOL), Gmail, and Microsoft, often involves automated systems that pre-fetch or "sandbox" every link within an email. A significant side effect of this essential security measure is the inadvertent activation of legitimate links, particularly one-click unsubscribe links. When these automated systems click an unsubscribe link that functions via a simple GET request, it can lead to "phantom unsubscribes," where subscribers are removed from a list without their explicit intent, resulting in artificially inflated unsubscribe rates.
Key findings
- Automated Link Scanning: Major email providers and security vendors, including Oath (Yahoo, AOL), Gmail, and Microsoft, actively scan and pre-fetch links in emails for security and anti-phishing purposes.
- Inadvertent Link Activation: This automated scanning process can inadvertently trigger legitimate links, including one-click unsubscribe links, as the systems are designed to visit every URL.
- Phantom Unsubscribes: The automated clicks on unsubscribe links lead to "phantom unsubscribes," where recipients are removed from email lists without their actual intent, skewing unsubscribe metrics.
- Impact on Deliverability: This phenomenon is a known challenge in email deliverability, affecting list hygiene and the accuracy of unsubscribe rate reporting.
Key considerations
- Unsubscribe Mechanism Design: To mitigate inadvertent unsubscribes, marketers should design unsubscribe links that require a confirmation step, such as a confirmation page or a POST request, rather than a simple one-click GET request.
- Monitoring Metrics: Email marketers should be aware that a portion of their reported unsubscribes may be due to automated bot clicks rather than direct user action, which could influence their interpretation of list health and engagement.
- Security vs. User Intent: Recognize the tension between necessary security measures employed by ISPs and the potential for these measures to inadvertently impact user-intended actions and data accuracy.
What email marketers say
11 marketer opinions
Yes, email link testing by providers such as Oath (Yahoo, AOL), Gmail, and other ISPs or security tools is a well-documented cause of inadvertent unsubscribes. This phenomenon occurs because automated systems are deployed to pre-scan and pre-fetch all links within emails for malicious content or security threats. During this process, legitimate links, including unsubscribe links, can be triggered automatically without any user interaction, leading to 'bot clicks' or 'phantom unsubscribes' that inflate reported unsubscribe rates.
Key opinions
- Automated Link Verification: Email providers and security platforms, including Oath, Gmail, and others, routinely employ automated systems to scan and pre-click links in incoming emails to check for security vulnerabilities and malicious content.
- Unintentional Link Activation: These automated link scanning processes can inadvertently activate legitimate links, most notably one-click unsubscribe links, as part of their security protocols.
- Spurious Unsubscribe Data: The result of these automated clicks is 'phantom' or 'bot' unsubscribes, where recipients are removed from mailing lists without their conscious intent, leading to artificially elevated unsubscribe metrics.
- Recognized Industry Challenge: This issue is widely acknowledged by email marketing experts and deliverability professionals as a significant factor affecting the accuracy of unsubscribe reporting and list hygiene.
Key considerations
- Unsubscribe Link Architecture: To mitigate unintended unsubscribes, marketers should design unsubscribe processes that require a secondary confirmation step, such as a confirmation page or a POST request, rather than a simple, direct GET request.
- Analyzing Unsubscribe Rates: Marketers should be aware that a portion of their reported unsubscribes may stem from automated security scans rather than genuine user action, necessitating careful interpretation of unsubscribe rate trends.
- Security Protocols Impact: It is important to understand that these automated clicks are a byproduct of necessary security measures by ISPs to protect users, despite their impact on deliverability metrics.
Marketer view
Email marketer from Email Geeks found evidence that link testing is occurring at Oath and also now at Gmail, leading to inadvertent clicks on all links.
17 May 2025 - Email Geeks
Marketer view
Email marketer from Word to the Wise explains that email providers like Yahoo (Oath) are known for scanning emails for malicious links, and this process can inadvertently click on valid links, including unsubscribe links, leading to phantom unsubscribes.
26 Aug 2022 - Word to the Wise Blog
What the experts say
3 expert opinions
Automated link testing by email providers and security vendors, particularly services like Oath (including Yahoo and sbcglobal), can indeed cause inadvertent unsubscribes. These systems systematically click all links within an email as part of their security protocols, validating destinations and scanning for malicious content. When an unsubscribe link is designed as a simple, one-click GET request, these automated clicks can process the unsubscribe action without any user intent. This leads to accidental subscriber removals, artificially inflating unsubscribe rates and impacting the accuracy of engagement metrics.
Key opinions
- Provider Link Testing: Email providers and security vendors, notably Oath (Yahoo, sbcglobal), employ automated systems that test links within emails by clicking them, primarily for security and validation purposes.
- Vulnerable Unsubscribe Links: If an unsubscribe link is set up as a simple, one-click GET request, these automated link testers can inadvertently trigger the unsubscribe action without any user interaction.
- Unintended Subscriber Removal: This automated activation leads to subscribers being removed from mailing lists without their consent or knowledge, resulting in 'phantom' unsubscribes.
- Impact on Metrics: The unintentional unsubscribes cause an artificial inflation of unsubscribe rates, skewing deliverability metrics and making accurate assessment of list engagement challenging.
Key considerations
- Require Confirmation: To prevent accidental removals, ensure unsubscribe processes incorporate a confirmation step, such as a dedicated landing page, to verify user intent.
- Utilize POST Requests: Configure unsubscribe links to use POST requests rather than simple GET requests, as this provides a safeguard against automated systems inadvertently triggering the unsubscribe action.
- Validate Unsubscribe Data: Understand that a portion of reported unsubscribes may be attributable to automated bot clicks, and consider this when analyzing list health and subscriber engagement metrics.
Expert view
Expert from Email Geeks explains that Oath (Yahoo, sbcglobal) might be using link testing, which could cause inadvertent clicks, and states that unsubscribe links should not work simply by following a link.
12 Mar 2022 - Email Geeks
Expert view
Expert from Spam Resource explains that automated link testing by email providers and security vendors, such as Oath, can inadvertently trigger unsubscribe links if they are simple GET requests. These systems click every link to test for malicious content or verify destinations, and a one-click unsubscribe URL can be processed without user intent, leading to accidental unsubscribes. To prevent this, he suggests that unsubscribe links should require a POST request or a confirmation page.
13 May 2022 - Spam Resource
What the documentation says
3 technical articles
Yes, email link testing by providers such as Oath, alongside security vendors like Mimecast and Microsoft, frequently causes inadvertent unsubscribes. This occurs because automated systems, including URL sandboxing and web crawlers, are designed to pre-scan and analyze links for malicious content before delivery. As a result, these 'bots and scanners' can inadvertently activate legitimate links, including one-click unsubscribe options, leading to unintentional subscriber removals, a known challenge in email deliverability.
Key findings
- Link Scanning Methods: Security services, like Mimecast's URL Protection and Microsoft's Safe Links, utilize advanced methods such as URL rewriting, sandboxing, and web crawling to analyze links in emails before delivery.
- Automated Link Activation: These automated scanning processes are designed to visit and evaluate links, which can inadvertently trigger any active URL, including unsubscribe links.
- Unintended Unsubscribes: The activation of unsubscribe links by these 'bots and scanners' leads to subscribers being removed from lists without their direct intent.
- Acknowledged Deliverability Factor: Email providers and deliverability experts, such as ActiveCampaign, recognize that automated clicks on unsubscribe links are a known cause of unintended unsubscribes and impact deliverability metrics.
Key considerations
- Multi-Step Unsubscribe: To minimize unintended unsubscribes, implement a multi-step unsubscribe process that requires user confirmation, such as a confirmation page, rather than a single-click action.
- Analyze Unsubscribe Trends: When reviewing unsubscribe rates, consider that a portion may be due to automated link testing by security systems, not actual user intent, which informs the true health of your list.
- Understand Security Protocols: Recognize that these automated link checks are essential security measures employed by providers to protect users, even if they occasionally impact unsubscribe accuracy.
Technical article
Documentation from Mimecast, an email security vendor, describes how their URL Protection service rewrites and analyzes links in emails before delivery. While not directly stating it triggers unsubscribes, this process involves "scanning and sandboxing" URLs, which is the underlying mechanism that can inadvertently activate links.
26 Jul 2022 - Mimecast
Technical article
Documentation from Microsoft describes Safe Links, a feature in Microsoft 365 Defender that scans URLs in email. This process involves a "web crawler" that visits the link to determine if it's malicious, illustrating the mechanism by which automated systems can inadvertently trigger unsubscribe links, even if not explicitly stated by Microsoft to do so for unsubscribes.
20 Jul 2022 - Microsoft Learn
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