What this checks,and why.
In one line
A DKIM checker validates that your selector publishes a public key in DNS and that signing aligns with your From domain.
Why it matters
DKIM failures break DMARC alignment and reduce trust with mailbox providers.
How to act on it
Verify selector CNAME/TXT records, key length, and signing coverage across your mail streams.
Read the result.
What DKIM checks cover
DKIM uses a selector (for example selector1._domainkey.yourdomain.com) publishing a public key.
The sending server signs headers and body; receivers verify the signature with the DNS-published key.
Common DKIM failures
Wrong selector after an ESP or provider migration, or rotated keys that were never updated in DNS.
Partial MIME signing across multipart messages, and a From domain that does not match the signing domain.
Questions, answered.
Yes for most modern programs. Many providers expect both SPF and DKIM, and DMARC policies often require alignment on at least one.
Fix it once.Watch it forever.
CloudJet re-checks every record on every sending domain daily and fixes drift before it costs you the inbox.