Email security

DMARC protects subdomains

SPF, DMARC, DKIM, MTA-STS: protection against spoofed mail in your name.

Why it matters

Attackers can spoof any subdomain (billing.example.com) even though the main domain is protected.

How to fix it

Quick fix · under 1 hour

Remove sp=none or set it to quarantine/reject.

Test this now, free: SPF, DMARC & DKIM checker - no sign-up.

How we test it

The check runs from the public internet as part of every scan, read-only and without touching your data. If it fails, your report shows the evidence that proves it - the record, header, file or banner we observed - together with the fix above, tailored to the issue we found.

Does your domain pass this check?

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