Free tool · Check
DKIM record checker
Enter a domain and selector to look up its DKIM key and check the key length and syntax. Don't know the selector? Leave it blank and we try the common ones.
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Add your domain and we give you the exact SPF, DKIM, DMARC and return-path records, check them for you, and sign every message with your own domain's key. Free for 3,000 emails a month.
Where to find your selector
Open any email you sent, view the original or raw source, and find the DKIM-Signature header. The s= tag is the selector and d= is the signing domain. The key lives at selector._domainkey.domain.
Your email provider also lists the selector in its DKIM or domain settings.
Go deeper: SPF, DKIM and DMARC for transactional email
Questions
What is a DKIM selector?
A name that tells receivers where to find the public key, so one domain can have several keys (one per provider, or old and new during a rotation). The key is published as a TXT record at selector._domainkey.yourdomain.com.
Is a 1024-bit DKIM key still OK?
It still verifies, but 2048-bit keys are the current recommendation and some receivers trust short keys less. Rotate to 2048 bits when you can.
What does t=y mean in a DKIM record?
Test mode: the domain is telling receivers not to treat failed signatures differently from unsigned mail. Remove it once signing works.