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Email authentication and deliverability

List-Unsubscribe header

An email header (RFC 2369) with a mailto or web address that mail apps use to show their own Unsubscribe button.

The header lists one or more addresses in angle brackets, for example a mailto address and an https link. Gmail, Yahoo, Apple Mail and Outlook read it and offer an Unsubscribe button next to the sender, which gives readers a way out other than the spam button. On its own it is not enough for bulk senders to Gmail and Yahoo, which also need the one-click variant.

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Related terms

  • One-click unsubscribe (RFC 8058): A standard way for mail apps to unsubscribe a reader with one POST request, required by Gmail and Yahoo for bulk senders since 2024.
  • DMARC alignment: The DMARC rule that SPF or DKIM only counts when its domain matches the domain in the visible From address.

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