List-Unsubscribe Checker for One-Click Unsubscribe
Paste the headers of an email you sent. See whether List-Unsubscribe, the One-Click header and the DKIM signature meet RFC 8058 and the Gmail and Yahoo rules, and build correct headers. Free, no sign-up, read in your browser.
Your Headers
List-Unsubscribe Header Generator
For your own sending code or a tool that lets you set headers. Account Engagement (Pardot) and Marketing Cloud Next add theirs on their own.
One per recipient and list, with a token nobody can guess.
List-Unsubscribe: <https://…>curlThen sign both headers with DKIM: their names must be in the signature’s h= list, for example h=from:to:subject:date:list-unsubscribe:list-unsubscribe-post. The link must unsubscribe on the POST itself, without a redirect, a login or a landing page.
How to Find the Email Headers
Check an email from a real send: test sends can behave differently, as in Marketing Cloud Next.
Outlook (new) and Outlook.com
Open the email, choose More actions > View > View message details and copy the text. Microsoft help (opens in a new tab)
Outlook (classic)
Open the email in its own window, then File > Properties, and copy the Internet headers box. Microsoft help (opens in a new tab)
Gmail
Open the email, click the three dots next to Reply, choose Show original, then Copy to clipboard. Google help (opens in a new tab)
Apple Mail
Select the email, then View > Message > All Headers, and copy the headers. In iCloud Mail on the web: More > Show All Headers. Apple help (opens in a new tab)
Yahoo Mail
Open the email, click More and choose View raw message. Yahoo’s help describes the older desktop version. Yahoo help (opens in a new tab)
What One-Click Unsubscribe Needs
Four parts. The checker tests the first three; the fourth only your server can show.
- 1
A List-Unsubscribe Header With One HTTPS Link
In angle brackets, separated by commas:
<https://…>, optionally a<mailto:…>beside it. Only one such header per email (RFC 2369). - 2
The One-Click Header, Word for Word
List-Unsubscribe-Post: List-Unsubscribe=One-Click. It tells the mailbox provider to send a POST instead of opening the link (RFC 8058). - 3
A DKIM Signature That Covers Both
Both header names in the signature’s h= list. Without it, receivers should not offer one-click (RFC 8058, section 4).
- 4
A Link That Unsubscribes on the POST
No redirect, no login, no cookies and no page to confirm on. The link itself must identify the recipient and the list.
Gmail, Yahoo and Microsoft Rules
Gmail requires one-click from bulk senders; Yahoo recommends it; Microsoft asks for a working link.
| Provider | Since | Applies to | One-click | Also |
|---|---|---|---|---|
| Gmail | 1 Feb 2024; one-click by 1 June 2024 | Bulk senders (5,000+ messages a day to Gmail accounts), marketing and subscribed mail | Required: one HTTPS link with List-Unsubscribe-Post. mailto alone doesn’t count | Visible unsubscribe link in the body; honour within 48 hours (recommended) |
| Yahoo | Feb 2024; one-click from June 2024 | Bulk senders, marketing mail | RFC 8058 POST highly recommended; mailto acceptable | Visible link in the body; honour within 2 days |
| Microsoft Outlook.com | 5 May 2025 | More than 5,000 messages a day | Not required; functional unsubscribe links recommended | SPF, DKIM and DMARC required |
For Pardot and Marketing Cloud Next
What Salesforce’s own help pages say, checked on 17 October 2026.
Account Engagement (Pardot)
Pardot adds List-Unsubscribe headers to every email it sends, Sales Emails included, and they can’t be changed (Salesforce Help, 21 February 2024). Salesforce says they meet the Gmail and Yahoo one-click rule; the body still needs an unsubscribe or preference center link (3 May 2024). Without a verified DKIM record your domain isn’t fully authenticated: paste a Pardot email above to see which domain signs the headers.
Marketing Cloud Next
Every email with a promotional classification carries a List-Unsubscribe header for one-click, and unsubscribes must be processed within 2 days (Salesforce Help, 28 September 2026). Sending needs an authenticated domain. The body’s unsubscribe link does nothing in test sends (23 March 2026), so check a real send.
Common One-Click Errors
What the checker reports and how to fix it.
- No List-Unsubscribe-Post. Mailbox providers open the link in a browser instead of unsubscribing in one click. Fix: Add
List-Unsubscribe-Post: List-Unsubscribe=One-Click - Only a mailto link. Doesn’t meet Gmail’s one-click rule. Fix: Add one HTTPS link.
- http:// link. One-click needs HTTPS. Fix: Switch the link to https.
- Wrong Post value. “One-Click” alone or other spelling is not the agreed value. Fix: Write exactly
List-Unsubscribe=One-Click - Headers not in DKIM h=. Receivers should not offer one-click. Fix: Let the sending tool sign both headers.
- Two List-Unsubscribe headers. Only one is allowed. Fix: Put all links into one header.
- Link opens a landing page. Google: doesn’t comply with RFC 8058. Fix: Unsubscribe on the POST itself.
- Link redirects. RFC 8058 forbids redirects; a redirected POST often turns into a GET. Fix: Answer the POST at the link itself.
List-Unsubscribe Checker FAQ
Short answers to what people ask about one-click unsubscribe.
What is the List-Unsubscribe header?
An email header that tells the mail app how to unsubscribe from a mailing list: a link, an email address or both, in angle brackets (RFC 2369). Gmail, Yahoo and Apple Mail turn it into an unsubscribe button next to the sender.
What is one-click unsubscribe (RFC 8058)?
A second header, List-Unsubscribe-Post: List-Unsubscribe=One-Click, which tells the mailbox provider to send a POST to the HTTPS link. The recipient is unsubscribed without opening a page.
Is a mailto link enough?
Not for Gmail: Google says mailto doesn’t meet its one-click rule for bulk senders. Yahoo accepts mailto but highly recommends one-click. Keep the mailto next to the HTTPS link for older mail apps.
Do I still need an unsubscribe link in the email?
Yes. Gmail and Yahoo ask bulk senders for a clearly visible unsubscribe link in the body as well. It may lead to a preference page.
Why doesn’t Gmail show the unsubscribe button?
Gmail shows it only for messages that pass its automated eligibility checks, and Yahoo only with enough reputation and engagement. Correct headers are the condition, not a guarantee.
Do transactional emails need one-click unsubscribe?
No. Google and Yahoo require it for marketing and subscribed messages; transactional mail such as receipts and password resets is excluded.
How fast must I process an unsubscribe?
Yahoo asks for 2 days, and Google recommends 48 hours. Salesforce gives 2 days for Pardot and Marketing Cloud Next.
Does Pardot add one-click unsubscribe?
Yes. Account Engagement adds List-Unsubscribe headers to every email automatically, and Salesforce says they meet the Gmail and Yahoo one-click rule. Paste a Pardot email’s headers above to see which domain signs them.
Why doesn’t the checker test my unsubscribe link?
A POST to the link would unsubscribe the recipient whose email you pasted. Test your endpoint with the curl command from the generator, using a test recipient’s token.
Are the headers I paste stored?
No. They are read in your browser. Only the name of the DKIM key (selector._domainkey.domain) goes to our server, which asks a public DNS resolver. Nothing is saved or logged.
More Free Tools
We Make Salesforce Marketing Work for You
Talk to a certified consultant, not a salesperson, and leave the first call knowing your next step.