Definition
One-click unsubscribe: An extension to List-Unsubscribe that adds the header List-Unsubscribe-Post: List-Unsubscribe=One-Click, letting the mail client unsubscribe the recipient with a single HTTPS POST and no further steps. Both headers must be covered by a valid DKIM signature, and Gmail expects requests honored within two days.
How one-click unsubscribe works
You add two headers. List-Unsubscribe holds an HTTPS URL (and optionally a mailto address). List-Unsubscribe-Post holds the fixed value List-Unsubscribe=One-Click, which tells the client it can unsubscribe with a single POST.
When the recipient clicks Unsubscribe in the inbox, the client posts List-Unsubscribe=One-Click to your URL. The URL must identify the recipient on its own, without cookies, logins or redirects to a page. RFC 8058 also requires a valid DKIM signature that covers both headers.
Who requires one-click unsubscribe
Google requires it from bulk senders, those sending more than 5,000 messages a day to personal Gmail accounts, on marketing and subscribed messages, along with a visible unsubscribe link in the body. Yahoo has the same requirement.
Transactional mail such as receipts and password resets does not need it. Most email platforms add the headers automatically on marketing sends.
Common one-click unsubscribe mistakes
Endpoints that only handle GET, or that answer the POST by showing a preference page instead of unsubscribing. Unsubscribe tokens that expire after a few days.
A DKIM signature that does not include the two headers in its h= list, and unsubscribes that are recorded but take longer than two days to reach every sending tool.
List-Unsubscribe: <https://example.com/unsub?u=8f3a2c91>, <mailto:unsub-8f3a2c91@example.com>
List-Unsubscribe-Post: List-Unsubscribe=One-Click
DKIM-Signature: v=1; a=rsa-sha256; d=example.com; s=s2026;
h=from:to:subject:date:list-unsubscribe:list-unsubscribe-post; ...How RocketVerifier handles it
Paste a message's raw headers into our free email header analyzer to read its SPF, DKIM and DMARC results, which matter here because both unsubscribe headers must be covered by a passing DKIM signature. Our DKIM checker confirms the signing key is published. Once someone unsubscribes, add them to your RocketVerifier suppression list and the address comes back as do_not_mail if it ever reappears in an upload.