Does the order of MAILTO and HTTPS in the List-Unsubscribe header matter?

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.

Email marketer from Reddit suggests that HTTPS unsubscribe should be prioritized as it provides a better user experience. Some ISPs/ESPs also prioritise this.

Marketer from Email Geeks shares that a few years ago, when they tested the order of list-unsubscribe headers, having mailto first resulted in significantly fewer RFC8058 unsubs. Back then, even Google stated that HTTPS must come first to be considered for one-click unsub. He suggests ordering by preference but notes that in the case of Google, mailto first was killing the one-click unsub. Can't say if that is still the case.

Email marketer from Email Vendor Blog recommends placing the HTTPS unsubscribe option first in the List-Unsubscribe header. They suggest this makes it easier for users to unsubscribe with one click, and improves email deliverability by reducing spam complaints.

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.

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.

Expert from Email Geeks explains that technically, the order of preference for list-unsubscribe headers is from first to last. He also mentioned that in practice, mailbox providers will order by the protocols they prefer. He recalls rare cases (Microsoft) where it mattered, but doesn’t believe that’s true today.

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).

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.

Documentation from M3AAWG suggests providing a clear and easy unsubscribe mechanism. Although they don't explicitly dictate the order of MAILTO and HTTPS, it implies HTTPS (one-click unsubscribe) should be prominent for better user experience and compliance.