Runs in your browser
DKIM lookup
Probe 21 common DKIM selectors.
The lookup goes from your browser straight to a public service. We never see the domain.
What this checks
DKIM signs outgoing mail with a private key, and publishes the matching public key as a DNS TXT record under a selector, like google._domainkey.<domain>. This tool probes 22 selector names used by common mail providers and reports the ones that answer.
What to look for
One matching selector is enough — most domains send through a single provider. A domain can be genuinely signing mail and still show nothing here if it uses a selector outside this list.
A limit worth knowing
Amazon SES signs with a random, per-identity selector that cannot be guessed. A domain sending through SES will often read as "no DKIM" here even though DKIM is switched on.