Free tool

One-click unsubscribe checker

Since 2024, Gmail and Yahoo require bulk/marketing senders to support RFC 8058 one-click unsubscribe: a List-Unsubscribe header with an HTTPS URI plus List-Unsubscribe-Post. A link in the email body — or a mailto-only header — does not satisfy Gmail. Paste the raw headers of a message you've sent to check yours.