DuckIntel / Security Tools
Free DMARC validator. Check SPF, DKIM, and DMARC DNS records for any domain. Get a letter grade (A–F) and remediation guidance.
The DMARC Validator checks the SPF, DKIM, and DMARC DNS records for any domain and assigns a letter grade from A to F based on the strength and completeness of the email authentication configuration. Paste any domain name to see the full DNS record content, identify specific issues, and get remediation guidance for each problem found.
Email authentication — SPF, DKIM, and DMARC — is the foundation of defense against email spoofing and phishing. Without properly configured SPF records, anyone can send email that appears to come from your domain. Without DMARC, even organizations with SPF and DKIM have no policy for what receivers should do when authentication fails. A properly configured DMARC policy at p=reject is one of the most effective controls against business email compromise.
SPF (Sender Policy Framework) records specify which mail servers are authorized to send email for a domain. DKIM (DomainKeys Identified Mail) adds a cryptographic signature to outgoing messages that receivers can verify. DMARC ties them together and tells receivers what to do with messages that fail — quarantine them, reject them, or deliver them anyway. The DMARC Validator shows the actual record content and explains any gaps or misconfigurations in plain English.
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