Bulk DMARC Checker with SPF, DKIM & MX Audit

Check the email authentication of up to 100 domains in one run. This bulk DMARC checker reads public DNS, parses the DMARC and SPF records, confirms MX hosts answer, probes the DKIM selectors you list, and returns one row per domain with a 0-100 score, a letter grade, the issues in priority order and the record to publish next.

The distinguishing field is nonexistentSubdomainPolicy: it exposes the np tag introduced by DMARC RFC 9989 in May 2026. The Actor also reports p and sp, so teams can compare the policy for the organizational domain, existing subdomains, and non-existent subdomains without opening DNS tools domain by domain.

SPF, DKIM and MX checks

SPF is read and returned raw, and multiple SPF records are flagged because receivers can treat them as invalid. MX presence and mail-host names are reported so a domain that sends mail without receiving it stands out. DKIM cannot be discovered without a selector name, so the Actor probes the selectors you pass and reports which ones resolved to a public key. "No tested DKIM selector found" means none of your selector names resolved, not that DKIM is absent.

Who uses this email authentication checker

• IT administrators auditing a portfolio of company domains.
• Email-deliverability agencies checking client DNS before a campaign.
• Security teams reviewing anti-spoofing posture after a domain migration.
• Marketing operations teams validating SPF, DKIM, and DMARC before changing providers.

Ready-to-run example

{
  "domains": ["example.com", "google.com", "dmarcwise.io"],
  "dkimSelectors": ["default", "google", "selector1", "selector2"],
  "issuesOnly": false
}

The default input is valid and runs without an API key, proxy, login, or external account.

Data returned for each domain

Each dataset item includes:

• the normalized domain, a 0–100 score, and a letter grade;
• the raw DMARC and SPF records;
• parsed DMARC p, sp, np, pct, rua, and ruf values;
• MX presence and mail-host names;
• which requested DKIM selectors were found;
• plain-language issues and recommended next actions;
• the exact audit timestamp.

A SUMMARY record contains the number of domains checked, the number needing attention, and the grade distribution. Enable Return only domains needing attention to make the dataset convenient for alerts or scheduled workflows.

Reading the result

A missing DMARC record is a high-priority issue. p=none is reported as monitoring-only rather than enforcement. Multiple DMARC records are flagged because receivers can treat them as invalid. A pct below 100 is shown explicitly. Absence of np is a recommendation, not automatically an error: under RFC 9989 the applicable parent policy still provides fallback behavior.

Before reading the DKIM column, add the selectors used by the domain’s mail providers: the check only covers the names you supply.

Limits and responsible use

• Maximum 100 domains per run.
• Maximum 20 DKIM selectors per run.
• Only public DNS records are queried.
• The output contains configuration data, not personal data.
• Scores are deterministic guidance, not a guarantee of inbox placement or complete RFC compliance.
• DNS caching and propagation can make recent changes appear later.

This Actor is an unofficial independent utility. It is not affiliated with the IETF, Google, Yahoo, Microsoft, or any email provider. Review proposed DNS changes with the person responsible for your mail system before applying them.