Glossary
List-Unsubscribe
Last reviewed 18 September 2026
What is the List-Unsubscribe header?
List-Unsubscribe is a message header offering machine-readable ways out of a list, and paired with a List-Unsubscribe-Post header carrying the value List-Unsubscribe=One-Click it is what a mail client uses to unsubscribe a reader without opening a browser.
Two headers do the work and one-click requires both. List-Unsubscribe on its own predates RFC 8058 and offers exits a client may choose to present; List-Unsubscribe-Post is the header that declares the https URI safe to POST to without asking the reader anything further. A message with the first and not the second does not have one-click unsubscribe, whatever the sending dashboard says.
The header value usually carries two exits in angle brackets, an https URI and a mailto. The https one is what one-click uses, and the mailto is the fallback for clients that prefer it.
See also
- One-click unsubscribe
One-click unsubscribe is a mail client operating the unsubscribe on the reader’s behalf by POSTing to an https URI the sender put in the message headers, with no browser, no confirmation page and no further interaction from the reader, as RFC 8058 defines it.
- Unsubscribe
An unsubscribe is a reader withdrawing permission to be mailed, and since February 2024 Google and Yahoo have required one to be honoured within two days, a much shorter clock than the 10 business days the United States CAN-SPAM Act allows.
- Bulk sender requirements
The bulk sender requirements are the list Google and Yahoo both began enforcing in February 2024: SPF and DKIM on the sending domain, a DMARC record on the From domain, one-click unsubscribe in the headers, unsubscribe requests honoured within two days, and a spam complaint rate under 0.3 per cent.
Read next
This term is covered properly in Unsubscribe requirements: one-click, List-Unsubscribe and two days, which is a longer piece on the subject.
Every other term is on the glossary index , the longer writing is in the guides, and what this site itself does is on the home page.
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