トTommy Slettvold
Free tool · Email security

Mail Shield

Can someone send email pretending to be your company? Enter your domain and see how well SPF, DKIM and DMARC protect it, with a plain-language fix for every problem.

DKIM selectors (optional, comma-separated)

Only public DNS data is read, straight from your browser. The domain is not stored or sent to me; the only requests go to DNS-over-HTTPS (Cloudflare, with Google as backup).

What the grade means

The grade weighs DMARC most, because it is the check that tells other mail servers to refuse fake mail. A domain without DMARC can't get better than D, and one that only monitors (p=none) can't get better than C. DKIM keys are found by guessing common selector names; if yours is not found, that does not mean it is missing.

New to all this? Read SPF, DKIM and DMARC for small businesses first.