List-Unsubscribe header
An RFC-defined email header that lets the recipient's client offer a one-click unsubscribe button — required by Gmail and Yahoo for bulk senders.
The List-Unsubscribe header is an RFC-defined email header (RFC 2369 / RFC 8058) that lets a recipient's mail client offer a native one-click unsubscribe button without requiring the user to find a footer link. Gmail surfaces the button at the top of marketing email; Outlook and others do similarly.
Modern compliance requires the one-click variant (RFC 8058) — both a mailto: link and an HTTPS URL — so the client can POST a single request to unsubscribe without the user landing on a confirmation page. Since 2024, Gmail and Yahoo require the one-click header for bulk senders (5,000+ messages/day to their domain).
Including List-Unsubscribe is now a baseline requirement, not an optimization. Most ESPs include it automatically; if you're running custom infrastructure, this is one of the first things to verify. Missing or incorrectly configured List-Unsubscribe directly impacts deliverability.