Machine-actionable unsubscribe mechanism using the List-Unsubscribe headers and one-click protocol.
Consent and message purpose
One-click unsubscribe
Machine-actionable unsubscribe mechanism using the List-Unsubscribe headers and one-click protocol.
Required by some mailbox-provider bulk-sender policies in addition to a visible link.
It is not merely any unsubscribe link in the message body.