This document describes a method for signaling a one-click function for the List-Unsubscribe email header field. The need for this arises out of the actuality that mail software sometimes fetches URLs in mail header fields, and thereby accidentally triggers unsubscriptions in the case of the List-Unsubscribe header field.| IETF Datatracker
This resource is for qualified high-volume senders. If you’re an everyday Gmail user| gmail.com
Sender Best Practices for mail deliverability| senders.yahooinc.com
Today, we’re announcing new requirements for bulk senders that will help keep Gmail safer and more spam-free.| Google