Recently on a call with Microsoft there was discussions around the functions of the Unsubscribe Header, which lead to the diagnosing of a possible bug regarding this x-header. The header is defined in RFC 2369.

This x-header is designed to send an unsubscribe request to predefined email of the senders and trigger removal of the users address. However in the Windows Live Hotmail – classic environment this was not happening as anticipated by Microsoft. The sender was added to the consumer’s blocked senders list but there was no trigger sent to the senders unsubscribe system.

Microsoft has informed senders that this bug has been addressed and the fix will be included in update released next week.

In addition, a Microsoft spokes person has provided the following updates regarding the list-unsubscribe x-header:

  • Both Windows Live Hotmail and Windows Live Hotmail Classic support list-unsubscribe URL and mailto
  • Unsubscribe only appears when the user has marked the sender as safe sender or they are deemed safe by our service, aka a “known sender” – When the sender has been added to address book
  • Unsubscribe no longer results in the address being added to your block list, but:
    • Unsubscribe results in the address being removed from your safe list
    • Unsubscribe using “mailto” results in us messaging the user that “We’ve asked the sender to remove you from this mailing list.”
    Note as with all services, this will evolve over time. We are continually looking to improve the user experience, provide increased level of user personalization while rewarding best of breed mailers committed to online safety and working to stem the tide of deceptive email and spam.”

This is good news for senders publishing the required x-List-Unsubscribe header as one of the previous actions on the unsubscribe button was to add you to the users block list. This effectively prevented users from resubscribing at a later time to your mailings without first removing you from the blocked list. This change will now remove that limitation.