Deliverability glossary · Updated 2026-08-10
One-click unsubscribe
Also called: RFC 8058
RFC 8058 one-click unsubscribe lets a mailbox provider opt a recipient out with a single POST request, no landing page and no confirmation step. Gmail and Yahoo require it from bulk senders.
It works through a companion header, `List-Unsubscribe-Post: List-Unsubscribe=One-Click`. When present alongside an HTTPS List-Unsubscribe URL, the provider POSTs to that URL directly when the recipient clicks unsubscribe in their interface.
The failure mode is specific and common: implementing the URL as a GET-only endpoint. The provider sends a POST, receives 405 Method Not Allowed, and the opt-out silently fails. The recipient believes they unsubscribed, keeps receiving mail, and reports spam the next time.
Correct behaviour is to accept POST at the same URL, process the opt-out without requiring a confirmation click, and return success. A landing page that asks "are you sure?" defeats the purpose and does not satisfy the requirement.
Because the address is embedded in a URL, it must be percent-encoded when written and decoded when handled. Plus signs in email addresses are the usual casualty.
How Raechly handles it
Both GET and POST are registered on the unsubscribe route, with the address percent-encoded in the header URL and unescaped in the handler. It was shipped as a fix after a GET-only route returned 405 to real one-click requests.
Related terms
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