DKIM checker
Enter a domain and a selector. We look up the DKIM key at selector._domainkey.domain and check that it’s usable. Don’t know the selector? Try the common ones.
The selector is in the DKIM-Signature header of an email from this domain, after «s=». Common ones: google (Google Workspace), selector1 and selector2 (Microsoft 365), k1 (Mailchimp), default, dkim, mail.
Watch this every hour, free.
Change email provider or rotate a key, and DKIM can disappear without anyone noticing. PingWise checks your selectors every hour, free, along with SPF and DMARC. How the monitor works.
Related tools: MX lookup · SPF checker · DMARC checker · Blacklist check · DNS lookup
What is DKIM?
DKIM (DomainKeys Identified Mail) adds a digital signature to every email you send. The receiving server fetches your public key from DNS and checks the signature, which proves the message really came from your domain and wasn’t changed on the way.
Why can’t you find my key without a selector?
DKIM keys sit under a name only the sender knows; DNS has no way to list them. That’s why we try the common ones.
Can I have more than one DKIM key?
Yes, one per selector. Each email service you send through usually has its own.
How long should the key be?
2048-bit. 1024-bit is the minimum most receivers accept.
How often can I check?
Up to 60 lookups an hour from your network. On the DKIM checker, «Try the common ones» counts as one.
Do you store what I look up?
We keep your IP address and the time for one hour, only to limit how often you can check. We don’t keep the domain or address you entered. Results are cached for a few minutes, so a repeat check may show the same answer.