Why doesn't Outlook webmail trigger List-Unsubscribe when using the quick action?
Summary
What email marketers say10Marketer opinions
Marketer from Email Geeks says he is checking documentation as Outlook.com only supports mailto, or at least used to, and that for some providers they choose whichever is listed first.
Email marketer from Reddit shares that `mailto` links can be unreliable due to spam filters and suggests the HTTPS version of List-Unsubscribe is more reliable, but some clients may not support it.
Email marketer from Email Marketing Blog notes that Outlook's algorithms may prioritize emails from senders with whom the user frequently interacts and may suppress the unsubscribe option for less engaged senders.
Email marketer from MailerMailer mentions that one reason for List-Unsubscribe not working in Outlook webmail could be related to the reputation of the sending domain, suggesting Outlook might deprioritize or ignore requests from senders with low reputation.
Email marketer from Microsoft Community explains that Outlook Webmail might use a combination of factors including user engagement, sender reputation, and content analysis to determine whether to display the unsubscribe option, and if the sender doesn't meet certain thresholds, the option may not appear.
Email marketer from Litmus responds that Outlook's behavior may be related to caching issues or inconsistencies in how it processes email headers, suggesting the quick action might rely on cached data that is not always up-to-date.
Email marketer from Reddit suggests that the issue could be due to the 'mailto' option being unreliable, especially if the receiving mailbox (the one defined in mailto) has spam filtering enabled, causing Outlook not to trigger the unsubscription.
Email marketer from EmailOnAcid responds that the reason could be due to Outlook's algorithms choosing to prioritize other factors over the List-Unsubscribe header, for example, user engagement or sender reputation.
Email marketer from SendGrid recommends ensuring the `List-Unsubscribe` header is correctly formatted and includes both the `mailto` and `https` versions, as Outlook might selectively choose one over the other based on its internal logic.
Email marketer from Stack Overflow shares that the List-Unsubscribe header might be ignored by Outlook webmail due to various reasons including Outlook using its internal mechanism for unsubscribing users or issues with the format/configuration of the List-Unsubscribe header itself.
What the experts say3Expert opinions
Expert from Word to the Wise responds that Outlook's inconsistent support for List-Unsubscribe could stem from its complex filtering algorithms that prioritize user engagement, sender reputation and content analysis. If the sender fails to meet certain thresholds, the unsubscribe option might not be displayed.
Expert from Email Geeks suspects that the List-Unsubscribe feature in Outlook is broken, referencing information from Pilar.
Expert from Word to the Wise shares insights that aggressive filtering by email clients such as Outlook will try to manage user's inboxes by any means necessary - this means that if a user doesn't often open an email, the unsubscribe link might be hidden in a bid to encourage a user to use Outlook's other inbox sorting features.
What the documentation says4Technical articles
Documentation from Microsoft explains that Outlook does support the List-Unsubscribe header, but its implementation may vary depending on the Outlook version and configuration. It recommends ensuring the header is properly formatted and accessible.
Documentation from SparkPost explains that the success of the List-Unsubscribe header depends on the receiving mail server's implementation and policies. Some servers might ignore the header if the sender doesn't meet certain reputation thresholds or authentication standards.
Documentation from RFC Editor explains that some email clients prioritize user experience over strict protocol adherence, which can lead to inconsistencies in handling List-Unsubscribe headers. It reinforces that both HTTP and mailto are valid but their handling is client-dependent.
Documentation from RFC Editor explains that the List-Unsubscribe header can be implemented using both HTTP and mailto URLs. If mailto is used, it depends on the client's configuration and the receiving server's handling of such requests, which might explain inconsistencies.