What does the letter grade mean?

A means MX, SPF, DMARC, and DKIM all pass. B and C mean one or more checks came back weak, like a p=none DMARC policy. D means SPF or DMARC is missing entirely. F means the domain has no MX records and cannot receive email at all.

Why do SPF, DKIM, and DMARC all matter for deliverability?

SPF lists which servers may send for the domain, DKIM cryptographically signs each message, and DMARC tells receivers what to do when both fail. Google and Yahoo have required all three from bulk senders since February 2024, so gaps directly cost inbox placement.

Can the tool miss a DKIM key that exists?

Yes. DKIM keys live under sender-chosen selectors, and the tool probes six common ones: google, default, k1, s1, selector1, and selector2. A domain signing under a custom selector will show a warning here even though its DKIM is fine, so the DKIM check warns rather than fails.

Test your email deliverability

One letter grade across MX, SPF, DMARC, and DKIM, with the weakness behind every lost point.

What you get

Four checks, one grade

MX, SPF, DMARC, and DKIM are queried concurrently and rolled into a single letter grade from A to F.

DKIM found without headers

The tool probes six selectors that cover Google Workspace, Microsoft 365, Mailchimp, and SendGrid, so you do not need a message sample.

Specific weaknesses named

Each check's summary states the exact problem, like a softfail-only SPF or a p=none DMARC policy, not just a score.

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Test your email deliverability

Four checks, one grade

DKIM found without headers

Specific weaknesses named

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