All glossary entries
Glossary

List-Unsubscribe header

An email header that gives mailbox providers a one-click way to unsubscribe — required by Gmail and Yahoo for senders over 5K/day.

The List-Unsubscribe header is a structured way to expose an unsubscribe URL or mailto address that mailbox providers can act on directly. Gmail and Yahoo started requiring it for "bulk senders" (5,000+ emails/day to their domains) in February 2024.

Missing or broken List-Unsubscribe at high volume is a deliverability death sentence — Gmail downgrades you to the spam folder for the entire affected domain.

BoomSauce adds a valid List-Unsubscribe header to every outbound message automatically, pointing at the platform-managed unsubscribe URL. Recipients clicking unsubscribe land on the suppression list immediately.

Related terms
Suppression list

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