DMARCguard DMARC Checker

Grade any site's DMARC, SPF, DKIM, MTA-STS and BIMI from A to F in one click, with the two fixes that matter most. No account.

Click the DMARCguard button on any website and it checks the domain behind the page. You see whether someone can send mail in its name, a 0-100 score weighted like the DMARCguard audit report, and what to change first. Use it on your own domain after a DNS change, on a client's or a prospect's before a call, or to vet a vendor that will email your staff. What it checks - DMARC: the policy receivers apply, including what a subdomain inherits - SPF: the whole include tree against the 10-lookup limit - DKIM: keys at the common selectors and their real key size - MTA-STS and TLS-RPT: the DNS records, and the policy file once you allow its one address - BIMI: the record and its DMARC prerequisite - DANE: TLSA records for every MX host - Blocklists: the domain's IP address on 12 major lists; a list that refuses public resolvers shows as not checkable, never as listed - DNS lookup: MX, TXT, A, NS and the other common record types Checks follow the current RFCs, including DMARCbis (RFC 9989). The side panel holds the full report and the findings for each protocol. Right-click a page or a link to check it. Privacy No account, no analytics, no tracking. Checks run in your browser, and DNS lookups go through Cloudflare's public DNS-over-HTTPS resolver. The extension has no access to the sites you visit: it reads the current tab's address only when you click its button or its right-click entry, never looks up names on a private network, and asks before it reads an MTA-STS policy file from a domain's server (you can withdraw that access in the extension's details). For daily DMARC reports, alerts and monitoring, DMARCguard's free plan covers up to 2 domains: https://dmarcguard.io/