What is RFC 8058 (List-Unsubscribe)?

RFC 8058 defines mechanisms for one click unsubscribe functionality through List-Unsubscribe and List-Unsubscribe-Post headers. This enables recipients to unsubscribe directly from their email interface without visiting external websites.

The RFC specifies header format, requirements for POST based unsubscribe handling, and security considerations. It creates standardized machine readable unsubscribe capabilities that mailbox providers can present consistently.

RFC 8058 became particularly important with Gmail and Yahoo's 2024 requirements mandating one click unsubscribe for bulk senders. The previously optional standard is now practically required for marketing email deliverability.