List-Unsubscribe header checker
Gmail and Yahoo expect bulk mail to carry a List-Unsubscribe header — and, for marketing messages, RFC 8058 one-click support alongside it. Upload your email and we’ll confirm the header is present and well-formed, in seconds. No signup, no data stored.
12 checks, in seconds
SPF authentication
DKIM signature
DMARC alignment
List-Unsubscribe header
One-click POST support
Visible unsubscribe link
Unsubscribe not gated
Physical mailing address
Honest subject line
Spam-trigger wording
Image-to-text balance
Link safety
Learn more
Gmail & Yahoo sender requirementsWhat bulk senders (5,000+/day) must do: authentication, one-click unsubscribe, and a low spam rate.RFC 8058 one-click unsubscribeThe exact List-Unsubscribe and List-Unsubscribe-Post headers, and how mailbox providers use them.CAN-SPAM checklistPhysical address, honest subject lines, and an opt-out you honor within 10 business days.