Summary
While RFC 2369 doesn't explicitly prioritize the order of MAILTO and HTTPS in the List-Unsubscribe header, the consensus from experts, marketers, and subsequent documentation (RFC 8058, M3AAWG) leans towards prioritizing HTTPS for its one-click unsubscribe functionality and better user experience. Technically, the order of preference is from first to last, but mailbox providers can reorder based on preferred protocols. Older tests showed that placing MAILTO first could negatively impact RFC8058 unsubs with certain providers. Ultimately, making unsubscribe as clear and easy as possible is key for compliance, sender reputation, and reducing spam complaints.
Key findings
- RFC 2369 Neutrality: RFC 2369 doesn't dictate the order of MAILTO and HTTPS.
- HTTPS for One-Click: HTTPS is preferred for one-click unsubscribe, as per RFC 8058.
- User Experience Focus: Prioritizing a clear and easy unsubscribe mechanism, implying HTTPS prominence (M3AAWG).
- Provider Flexibility: Mailbox providers may reorder protocols based on their preference.
- Potential Historical Issues: Placing MAILTO first historically impacted RFC8058 with some providers.
- Technically First to Last: Technically, the order of preference is from first to last.
Key considerations
- HTTPS Prominence: Give prominence to HTTPS for its one-click unsubscribe benefits.
- User-Centric Design: Design the unsubscribe process to be as easy and clear as possible for users.
- Compliance: Ensure the unsubscribe process is compliant with relevant regulations.
- Provider Behavior: Be aware that providers may handle List-Unsubscribe differently.
- Testing: Consider testing different orderings to assess impact on your audience.
What email marketers say
4 marketer opinions
Several sources suggest that while the technical order of MAILTO and HTTPS in the List-Unsubscribe header might not always be strictly enforced, prioritizing HTTPS is generally recommended. This is primarily due to the improved user experience afforded by one-click unsubscribe, which can also positively impact sender reputation and reduce spam complaints. However, older tests indicate that some providers, like Google, may have required HTTPS to be listed first for one-click unsubscribe to function correctly, although this behavior might not persist.
Key opinions
- HTTPS Preference: Prioritizing HTTPS for one-click unsubscribe is generally recommended for a better user experience.
- Potential ISP/ESP Prioritization: Some ISPs/ESPs might prioritize or prefer HTTPS for unsubscribe processing.
- Historical Impact on RFC8058: Older tests indicated that placing MAILTO first could negatively impact RFC8058 (one-click) unsubscribe functionality, particularly with Google.
- Positive Impact: HTTPS can improve sender reputation and reduce spam complaints.
Key considerations
- User Experience: Focus on providing the easiest and most convenient unsubscribe option for users.
- Provider Behavior: Be aware that different email providers might handle List-Unsubscribe headers differently.
- Testing: Consider testing different orderings to assess the impact on your specific audience and sending environment.
- Compliance: Make it easy for your customers to unsubscribe.
Marketer view
Email marketer from StackOverflow notes, in a discussion, that while the order might not strictly matter technically, placing the more convenient unsubscribe option (likely HTTPS) first is better for user experience, potentially improving sender reputation.
29 Mar 2023 - StackOverflow
Marketer view
Email marketer from Reddit suggests that HTTPS unsubscribe should be prioritized as it provides a better user experience. Some ISPs/ESPs also prioritise this.
10 May 2024 - Reddit
What the experts say
3 expert opinions
Experts generally agree that while technically the order of MAILTO and HTTPS in the List-Unsubscribe header may not always matter, prioritising HTTPS for one-click unsubscribe is best practice. The order of preference is technically first to last, but mailbox providers will order by the protocols they prefer. Making it as easy as possible for customers to unsubscribe is key for user experience and compliance.
Key opinions
- Technical Order: Technically, the order of preference is from first to last.
- Provider Preference: Mailbox providers may re-order based on their preferred protocols.
- User Experience: HTTPS for one-click unsubscribe improves user experience.
- Clarity: Making unsubscribe clear and easy is critical.
Key considerations
- HTTPS prominence: Ensure HTTPS is prominent for one-click unsubscribe benefits.
- Provider Behaviour: Acknowledge that providers may re-order protocols.
- Ease of Unsubscribe: Focus on making the unsubscribe process straightforward for users.
- Potential compliance issues: May be a compliance issue if not providing an easy unsubscribe option
Expert view
Expert from Spam Resource (John Levine) discusses list-unsubscribe best practices, suggesting providing both MAILTO and HTTPS options. While he doesn't explicitly state the order preference, the implication is that HTTPS, for one-click unsubscribe, should be prominent for better user experience and compliance.
26 Sep 2024 - Spam Resource
Expert view
Expert from Word to the Wise explains it is important to make unsubscribe clear. While the order of mailto: and one-click unsubscribe may not matter at the technical level, you must make it easy for your customers to unsubscribe.
5 Feb 2024 - Word to the Wise
What the documentation says
3 technical articles
While the formal documentation (RFC 2369) doesn't specify the order of MAILTO and HTTPS in the List-Unsubscribe header, subsequent specifications (RFC 8058) and best practice recommendations (M3AAWG) imply a preference for HTTPS due to its one-click unsubscribe functionality. The emphasis is on providing a clear and easy unsubscribe mechanism, suggesting that HTTPS should be prominently featured.
Key findings
- No Explicit Prioritization: RFC 2369 does not explicitly prioritize MAILTO or HTTPS order.
- HTTPS Implication: RFC 8058 implies preference for HTTPS through its definition of one-click unsubscribe.
- User Experience Focus: M3AAWG emphasizes clear and easy unsubscribe, implying HTTPS prominence.
Key considerations
- One-Click Emphasis: Give importance to providing one-click unsubscribe functionality (HTTPS).
- Clarity and Ease: Prioritize clarity and ease of unsubscribe for the user.
- Best Practices: Adhere to best practices that promote convenient unsubscribe methods.
Technical article
Documentation from ietf.org (RFC 8058) defines a method for one-click unsubscribe using a HTTP POST request. While this RFC doesn't directly address the order of MAILTO and HTTPS entries in the List-Unsubscribe header, its existence implies that HTTPS is preferred for ease of use (one-click).
26 Apr 2022 - ietf.org
Technical article
Documentation from ietf.org (RFC 2369) specifies the format and semantics of the 'List-Unsubscribe' header field, noting that it allows users to easily unsubscribe from mailing lists. While it describes the header's structure, it doesn't explicitly prioritize the order of MAILTO and HTTP/HTTPS unsubscribe options.
22 Mar 2023 - ietf.org
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