Summary
Outlook supports both mailto and HTTP List-Unsubscribe headers. Its display depends on factors like sender reputation, email authentication (SPF, DKIM, DMARC), content, and recipient email client settings. Webmail clients have requirements for mailto links to prevent abuse, and Microsoft is working to fix related issues. Proper implementation, monitoring sender IP using SNDS, prompt honoring of requests, and adhering to CAN-SPAM are critical for compliance and a good sender reputation.
Key findings
- Supported Headers: Outlook supports both mailto and HTTP List-Unsubscribe headers for unsubscribing.
- Reputation is Key: Sender reputation significantly affects header display; a good reputation helps.
- Authentication Matters: Correct SPF, DKIM, and DMARC email authentication increases header display likelihood.
- Mailbox Provider Control: Mailbox providers control UI and can hide headers based on reputation/spam flags.
- Compliance: Using List-Unsubscribe helps comply with CAN-SPAM and anti-spam legislation.
Key considerations
- Monitor Sender IP: Utilize Microsoft SNDS to monitor and resolve deliverability concerns for the sender IP address.
- Authenticate: Implement and verify SPF, DKIM, and DMARC records for the sending domain.
- Check Content: Ensure email content avoids spam triggers to prevent filtering and maintain reputation.
- Honor Unsubscribes: Process unsubscribe requests promptly to meet legislative requirements.
- Test Implementation: Verify list-unsubscribe functions correctly across multiple email clients
What email marketers say
10 marketer opinions
The List-Unsubscribe header in Outlook supports both mailto and HTTP options, offering users a way to unsubscribe directly from their email client. However, its display is not guaranteed and depends on several factors, including sender reputation, email authentication (SPF, DKIM, DMARC), email content, and the recipient's email client settings. Mailbox providers ultimately control the UI and may hide or ignore the header for senders with poor reputations or emails flagged as spam. Compliance with regulations like CAN-SPAM and adherence to email best practices are crucial for ensuring the List-Unsubscribe header is displayed and effective.
Key opinions
- Supported Options: Outlook supports both mailto and HTTP List-Unsubscribe headers.
- Reputation Matters: Sender reputation significantly impacts whether the List-Unsubscribe header is displayed.
- Authentication is Key: Proper email authentication (SPF, DKIM, DMARC) increases the likelihood of the header being shown.
- Mailbox Provider Control: Mailbox providers have the final say on whether the header is displayed, based on various factors.
- Regulatory Compliance: Using List-Unsubscribe helps comply with regulations like CAN-SPAM.
Key considerations
- Monitor Reputation: Regularly monitor sender reputation scores to identify and address any deliverability issues.
- Implement Authentication: Ensure proper email authentication protocols (SPF, DKIM, DMARC) are correctly configured.
- Follow Best Practices: Adhere to email best practices, including content guidelines, to avoid being flagged as spam.
- Provide Visible Unsubscribe: Even if the List-Unsubscribe header isn't displayed, ensure a visible and easy-to-use unsubscribe link is included in the email body.
- Test Implementation: Thoroughly test List-Unsubscribe implementation across different email clients to ensure compatibility.
Marketer view
Email marketer from EmailOctopus shares that the List-Unsubscribe header might not display due to factors like low sender reputation, missing DKIM/SPF records, or the email client's filtering algorithms. They recommend ensuring proper email authentication and maintaining a good sender reputation to improve display rates.
24 Jan 2025 - EmailOctopus
Marketer view
Email marketer from Reddit shares the view that Outlook's display of the 'Unsubscribe' option depends on the sender's reputation and the email's content. Senders with a good reputation are more likely to have the option displayed prominently.
1 Apr 2023 - Reddit
What the experts say
4 expert opinions
Outlook supports both mailto and URL-based List-Unsubscribe headers, displaying them in both web and desktop clients. However, the appearance of a quick unsubscribe snippet depends on the sender's reputation, and some webmail clients have specific requirements for mailto links to prevent abuse. Microsoft is aware of and addressing issues with List-Unsubscribe functionality. Implementing and promptly honoring unsubscribe requests is critical for regulatory compliance and maintaining a legitimate bulk email program.
Key opinions
- Supported Headers: Microsoft supports both mailto and URL-based List-Unsubscribe headers in Outlook.
- Reputation Threshold: Quick unsubscribe snippet visibility is tied to sender reputation.
- Mailto Requirements: Webmail clients may have extra mailto link requirements to prevent mailbombing.
- Microsoft Awareness: Microsoft is working on fixing known issues with List-Unsubscribe functionality.
- Regulatory Compliance: Implementing List-Unsubscribe is essential for complying with anti-spam laws.
Key considerations
- Monitor Reputation: Pay close attention to sender reputation to ensure snippet visibility.
- Verify Mailto Links: Ensure mailto links meet webmail client requirements to avoid deliverability issues.
- Stay Updated: Keep abreast of updates from Microsoft regarding List-Unsubscribe fixes.
- Honor Unsubscribes Promptly: Comply with unsubscribe requests immediately to maintain a positive sender reputation.
- Implement Correctly: Verify List-Unsubscribe implementation for best delivery outcomes.
Expert view
Expert from Email Geeks explains that some webmail clients only show the quick unsubscribe snippet for domains that meet a minimum reputation standard. They may also have extra requirements for mailto links, such as the domain in the mailto matching the authenticated domain in the message, to avoid mailbombing.
9 Nov 2022 - Email Geeks
Expert view
Expert from Word to the Wise answers question that Microsoft is using List-Unsubscribe header. Microsoft surfaces the list-unsubscribe header in both the Outlook web client and in Outlook desktop, and supports both mailto and URL based unsubscription.
22 Nov 2021 - Word to the Wise
What the documentation says
4 technical articles
Outlook supports both mailto and HTTP List-Unsubscribe headers, allowing users to unsubscribe either via email or a webpage. Official specifications detail the syntax and semantics for these options, emphasizing proper formatting for compatibility. RFC 8058 further specifies a one-click unsubscribe method. Microsoft's SNDS provides data to troubleshoot deliverability issues related to List-Unsubscribe.
Key findings
- Supported Headers: Outlook supports both mailto and HTTP List-Unsubscribe headers.
- Standard Specifications: RFC 2369 details the standard syntax and semantics for List-Unsubscribe headers.
- One-Click Unsubscribe: RFC 8058 specifies a one-click unsubscribe option.
- Troubleshooting Tool: Microsoft SNDS provides data for troubleshooting List-Unsubscribe related deliverability issues.
Key considerations
- Implement Correctly: Adhere to official specifications (RFC 2369, RFC 8058) when implementing List-Unsubscribe.
- Use Both Options: Consider implementing both mailto and HTTP options to cater to different user preferences.
- Monitor Deliverability: Utilize Microsoft SNDS to monitor and address any List-Unsubscribe related deliverability problems.
- Ensure Compatibility: Verify proper formatting of the List-Unsubscribe header for compatibility across email clients.
Technical article
Documentation from Microsoft Learn explains that Outlook supports both mailto: and HTTP List-Unsubscribe headers. The mailto: option allows users to unsubscribe via email, while the HTTP option directs them to a webpage for unsubscribing.
3 Apr 2022 - Microsoft Learn
Technical article
Documentation from Microsoft offers access to data about your sending IP address. This can be used to help solve deliverability issues, including list-unsubscribe problems.
24 Sep 2023 - Microsoft
Are mailto links compliant with Google and Yahoo's one-click unsubscribe requirements?
Can spam filters trigger email unsubscribes and how to prevent it?
Can the blue list header unsubscribe in Gmail be changed back to grey?
Does Google require List-Unsubscribe for one-click unsubscribe in emails?
How can I verify if my company's emails have List-Unsubscribe headers correctly configured?
How do Gmail and Yahoo's new one-click unsubscribe requirements work?
