Free local sender preflight
See what a final email can—and cannot—prove before a bulk send.
Compare the original message artifact with current Google, Yahoo, Microsoft, and RFC 8058 requirements. MailDNS reports header evidence honestly and leaves infrastructure or provider telemetry as not checked.
No upload or network check
Paste raw source or open an EML. The message never leaves this browser tab.
Artifact evidence only
Inspect identity headers, reported authentication, alignment, MIME, and one-click unsubscribe structure.
No invented compliance score
DNS, PTR, TLS, reputation, spam rates, endpoint behavior, and delivery remain explicitly not checked.
Paste or choose an original email
Parsing stays in this browser tab. MailDNS makes no network request and does not upload, store, or transmit the message. Maximum size: 5.0 MB.
Include all headers and MIME body. A forwarded copy is not the same as the original source.
One-click rules differ by message purpose. MailDNS will not guess it from the subject or content.
Primary requirements used
Provider policies change. Each result shows the provider scope and version date used by this preflight. RFC 8058 additionally requires a valid DKIM signature that covers both unsubscribe headers; this local tool can observe the DKIM h= list and receiver-reported result but does not cryptographically verify the signature or call the HTTPS endpoint.