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DKIM selector not found

DKIM selector not found

The selector DNS record cannot be located.

Reading time:: 5 min
Difficulty:: Intermediate
Estimated duration:: 5 min
Prerequisites:: None
Last updated:: 2026-07-15
Author:: empire

Problem summary

The selector DNS record cannot be located.

Severity: High

Symptoms

dkim=fail/temperror with missing key DNS
No TXT/CNAME at selector._domainkey.example.com
Signing enabled before DNS propagation

Possible causes

Selector hostname typo
DNS not published or published under wrong domain
CNAME target missing

How to diagnose

Read s= and d= from DKIM-Signature
Query selector._domainkey.<d-domain> at the authority
Confirm CNAME chain if the ESP uses delegated keys

How to fix

Publish the provider’s DKIM DNS exactly (example name): selector._domainkey.example.com
Fix typos; wait for authoritative visibility before signing
Disable signing until the key record resolves

How to verify

Selector resolves authoritatively
Test message shows dkim=pass

Prevention

Publish DNS first, enable signing second
Record selector names in the domain runbook

When to escalate

Production mail is failing for a material share of recipients after remediation attempts

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DKIM body hash mismatchBody modifications invalidate the DKIM body hash.
DKIM key too shortDKIM key length is below accepted operational guidance.
DKIM passes but DMARC failsDKIM validates but signing domain does not align for DMARC.
DKIM public key invalidPublished DKIM key material cannot be used for verification.
DKIM signature missingMessages leave without a verifiable DKIM signature.
DKIM signing-domain mismatchUnexpected d= domain relative to the visible From domain.
DKIM verification failureReceivers cannot validate the DKIM signature.

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DKIMCoreDKIM key and signature oriented validation utilities.

PreviousDKIM public key invalid NextDKIM signature missing

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