Email authentication, demystified.

Free, instant SPF, DKIM, DMARC, BIMI checks for any domain.
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Or pick a specific tool

Targeted checkers for each standard, plus generators for SPF and DMARC.

All checks in one click. Letter grade + per-section findings.

Parse a record, count DNS lookups, catch the 10-lookup limit.

Pick ESPs + IPs and get a clean record.

Read the policy at _dmarc.{your-domain}.

Wizard for a safe, conservative DMARC record.

Look up a selector and inspect the key.

Probe 50+ known ESP selectors automatically.

List mail exchangers + resolve A/AAAA in parallel.

Verify logo + DMARC enforcement + VMC.

Short, opinionated guides written for people, not RFCs.

The list of servers allowed to send mail as you.

How outgoing mail is cryptographically signed.

The standard that finally blocks spoofed mail.

Week-by-week from p=none to p=reject.

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