List-Unsubscribe Header Builder (RFC 8058)
Build List-Unsubscribe and one-click List-Unsubscribe-Post headers from a mailto and/or URL.
Overview
Builds the List-Unsubscribe and List-Unsubscribe-Post email headers for one-click unsubscribe per RFC 8058. Enter a mailto address, an HTTPS unsubscribe URL, and an optional subject, and the tool assembles the correct header lines and reminds you of the Gmail/Yahoo 2024 bulk-sender rules. Useful for email developers and deliverability engineers.