DKIM record checker
DKIM signs your mail with a private key and publishes the matching public key in DNS. Checking it needs the selector, which is the part almost nobody remembers — so this tool tries the common ones for you.
Free, no signup, no daily limit. We do not store what you check here.
Why the selector matters
A domain can publish many DKIM keys, one per sending service, each under its own selector at selector._domainkey.yourdomain.com. There is no way to list them from outside: DNS answers questions, it does not enumerate. So a checker either asks you for the selector or guesses common ones, and a domain reporting "no DKIM" usually means the selector was wrong rather than the key missing.
What DKIM does that SPF cannot
SPF authorises servers by address, so it breaks the moment a message is forwarded: the forwarding server is not on your list. DKIM signs the message itself, and the signature survives forwarding intact. That is why DMARC accepts either, and why a domain relying on SPF alone loses authentication on every forwarded message.
Questions
It says no record found. Is my DKIM broken?
Probably not. It most likely means we did not guess your selector. Look at the DKIM-Signature header of a message you sent: the s= value is the selector. Then check it explicitly as selector:yourdomain.com.
Should the key be 1024 or 2048 bits?
2048 where your provider supports it. 1024 is still widely accepted but is the weaker choice, and some receivers have begun treating short keys less favourably.
Related tools
SPF record checker
Check a domain SPF record for syntax problems, soft-fail settings and the 10-lookup limit. Free.
DMARC record checker
Check a domain DMARC policy, alignment and reporting setup. Free live DNS lookup, no signup.
Email deliverability check
One check for MX, SPF, DMARC and DKIM on your sending domain, with what to fix first. Free, no signup.
When you need more than a free tool
This page answers what can be determined offline and from public DNS. The API adds live carrier and mailbox verification, a calibrated confidence score, and the full evidence trail behind every verdict.
Credits never expire. Inconclusive verdicts are never billed. Cancel in one call. See pricing or read the docs.