List-Unsubscribe Header Checker – One-Click Unsubscribe Compliance
Check that your emails include List-Unsubscribe and List-Unsubscribe-Post so Gmail and Yahoo can offer one-click unsubscribe. Required for bulk senders; good practice for everyone.
What we check
- List-Unsubscribe — Present and valid. Values in angle brackets: mailto: and/or https: URL.
- List-Unsubscribe-Post — List-Unsubscribe=One-Click when you support one-click (POST) unsubscribe.
- Format — RFC-style syntax so receivers accept the header.
Common pitfalls
- Missing List-Unsubscribe entirely (required by Gmail/Yahoo for bulk).
- Missing List-Unsubscribe-Post when you support one-click (required for best treatment).
- Invalid mailto or URL (broken links, missing angle brackets).
- Unsubscribe endpoint that requires login or doesn’t accept POST for one-click.
Check my List-Unsubscribe headers
We check SPF, DMARC, and List-Unsubscribe in one scan. No signup required.
FAQ
What is the List-Unsubscribe header?
It's an optional HTTP-style header in email that tells inboxes how users can unsubscribe. Format is List-Unsubscribe: <mailto:...> or <https://...>. Gmail and Yahoo use it for one-click unsubscribe.
What is List-Unsubscribe-Post?
List-Unsubscribe-Post: List-Unsubscribe=One-Click tells receivers you support one-click unsubscribe (e.g. POST to a URL without the user opening a page). Required by Gmail/Yahoo for bulk senders in 2024.
Why does my check fail?
Common causes: header missing, invalid format (e.g. missing angle brackets, bad mailto/URL), or List-Unsubscribe-Post missing when you're sending bulk. Some providers require both mailto and https.
Do you send email or modify my messages?
No. We only run read-only checks. We don't send email or change your headers.
Related reading
Read-only checks. We don't send email or modify DNS. How we check