Deliverability & the inbox
List-Unsubscribe header
Also known as: List-Unsubscribe · one-click unsubscribe
An SMTP header that lets mailbox providers render a native one-click unsubscribe button — required for bulk senders by Gmail and Yahoo since 2024.
The List-Unsubscribe header (RFC 2369/8058) is an SMTP header the sender attaches to every email, containing a mailto: address or HTTPS URL that the mailbox provider can use to process unsubscribes without the user visiting the email body. Native one-click unsubscribe UIs in Gmail and Yahoo render from this header. Gmail and Yahoo's 2024 sender requirements mandate List-Unsubscribe for any sender exceeding 5,000 messages/day to their domains. The sender must honour the request within one or two business days — failing to process a List-Unsubscribe click is a major spam-rate signal to the mailbox provider. Most ESPs add the header automatically but operators should verify with a live test that clicking the native button actually suppresses the user in their system.