What this tool checks
DKIM adds a cryptographic signature to your outgoing email so receivers can verify it wasn't altered and really came from your domain. DKIM keys live in DNS under a named selector, so this checker probes the common selectors (default, google, selector1/2, and more) and reports which DKIM keys are published, alongside your SPF and DMARC. If you use a custom selector, your DKIM may still be valid even when it isn't auto-detected here.
Frequently asked questions
What is a DKIM selector?
A selector is a label that points to a specific DKIM public key in DNS, at selector._domainkey.yourdomain.com. It lets a domain rotate keys and run multiple senders. This tool tries the selectors most providers use.
My DKIM isn't detected, is it broken?
Not necessarily. If your mail provider uses a custom selector this tool doesn't probe, your DKIM can be fully working. Check your provider's DNS instructions for the exact selector name.
How does DKIM relate to SPF and DMARC?
DKIM proves a message wasn't tampered with; SPF authorizes sending servers; DMARC ties them together and sets a policy. You want all three, which is why this tool shows them together.