List-Unsubscribe Header Checker
Paste original email headers and check whether List-Unsubscribe and List-Unsubscribe-Post are set up for one-click unsubscribe.
Start Here
Enter the original email headers and run List-Unsubscribe Header Checker.
Review the Unsubscribe Header Checker Result
Review the status, warnings, and recommended actions shown in the result panel.
Ready When You Are
Run List-Unsubscribe Header Checker to see the Unsubscribe Header Checker result and next actions.
About List-Unsubscribe Header Checker
List-Unsubscribe is an email header that lets inboxes show an unsubscribe action near the sender name. List-Unsubscribe-Post adds the one-click signal used by inboxes that support RFC 8058. Together, these headers help people leave marketing email without hunting through the message body or marking the message as spam. Read One-Click Unsubscribe and Opt-Outs for the full background.
This checker is focused on the unsubscribe header pair only. It looks for the List-Unsubscribe header, an HTTPS unsubscribe URL, the exact List-Unsubscribe-Post value, an optional mailto fallback, duplicate header mistakes, and clues about whether DKIM signs the unsubscribe headers. It does not send an unsubscribe request or prove the endpoint works. After fixing the headers, send a fresh test email and check the original headers again.
What List-Unsubscribe Header Checker Checks
- List-Unsubscribe header presence
- HTTPS one-click unsubscribe URL
- List-Unsubscribe-Post one-click value
- Optional mailto fallback
- Duplicate or malformed unsubscribe headers
- DKIM signature coverage clues for unsubscribe headers
Questions
Does this tool send an unsubscribe request?
No. It only reads the headers you paste. It does not click, post, or test the unsubscribe URL.
Is a mailto unsubscribe enough for one-click unsubscribe?
No. A mailto option can be a useful fallback, but one-click unsubscribe needs an HTTPS URL in List-Unsubscribe and the List-Unsubscribe-Post header.