Glossary
List-Unsubscribe Header
The List-Unsubscribe header (RFC 2369, extended by RFC 8058) lets mail clients show an unsubscribe button next to the message. Bulk senders to Google and Yahoo require one-click unsubscribe support — List-Unsubscribe-Post enables one-click HTTP without a landing page in compliant clients.
Implementation
ESP dashboards often toggle this — your job is DNS/auth alignment for the sending domain, not the header syntax alone.
FAQ
Is List-Unsubscribe required?
For bulk marketing to major providers — yes, as part of bulk sender requirements.
What’s the difference between mailto and https?
mailto: opens a client; https: + POST enables one-click in supporting clients.
Does unsubscribe affect deliverability?
High complaint rates hurt — easy unsubscribe reduces “report spam” clicks.