RFC 8058 one-click unsubscribe validator
RFC 8058 one-click unsubscribe needs two things: a List-Unsubscribe header with an HTTPS URL, plus List-Unsubscribe-Post: List-Unsubscribe=One-Click. Upload your .eml and we’ll validate both headers are present and correctly formed. (The spec also requires a DKIM signature covering those headers — confirm that at send time.)
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.