Google and Yahoo require all senders dispatching over 5,000 messages daily to support RFC 8058 One-Click List-Unsubscribe headers, allowing recipients to safely opt out directly from the inbox interface.
1. Technical Header Implementation Syntax
📋 Required RFC 8058 Header Format
List-Unsubscribe: <https://emailcampaigner.info/api/unsubscribe?id=usr_89234&token=e47a8b>, <mailto:unsub@emailcampaigner.info?subject=unsub_usr_89234>
List-Unsubscribe-Post: List-Unsubscribe=One-Click| Header Attribute | Technical Requirement | Behavior |
|---|---|---|
List-Unsubscribe | HTTPS URL and/or Mailto URI | Provides automated unsubscribe endpoint |
List-Unsubscribe-Post | Exact string: List-Unsubscribe=One-Click | Triggers native single-click button in Gmail / Yahoo UI |
| HTTP Method Expected | POST to specified HTTPS URL | MTA receives un-authenticated automated payload |