List-Unsubscribe

Header telling the recipient how to unsubscribe. Mandatory for marketing email since 2024.

List-Unsubscribe (RFC 2369, updated by RFC 8058) is an email header telling the recipient how to unsubscribe via URL or mailto:.

Example: `List-Unsubscribe: <mailto:unsub@example.com?subject=unsubscribe>, <https://example.com/unsub?token=abc>`

Since 2024 Gmail and Yahoo require this header for all bulk senders. Messages without it land in spam.

Sendersy adds List-Unsubscribe automatically on every send. It also adds List-Unsubscribe-Post: List-Unsubscribe=One-Click (RFC 8058) — this lets mail clients fire a POST request for instant one-click unsubscribe without opening a page.