Invalid DKIM Key
An invalid DKIM key means the public key published in DNS is malformed, incomplete, or incorrectly formatted. DKIM verification depends on the receiver being able to parse the key exactly as published. If the key is truncated, split incorrectly, copied with missing characters, or contains the wrong DNS value, the receiver cannot use it to verify the signature.
One-Minute Fix
Re-copy the DKIM public key from your mail provider and publish it exactly as provided, without changing characters, spacing, or line breaks.
selector1._domainkey.example.com TXT "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQE..."The important part is publishing the exact provider-generated value without truncation or editing.
Re-checkWrong vs correct setup
Wrong setup
selector1._domainkey.example.com TXT "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0B...BROKEN_OR_TRUNCATED"This fails because the public key is incomplete or malformed. Even one damaged section can make the entire DKIM record unusable.
Correct setup
selector1._domainkey.example.com TXT "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQE..."This is the correct pattern. The DKIM public key is published exactly as generated by the provider, so receivers can parse it and verify signatures.
Why this happens
This usually happens when DNS editors wrap long TXT values incorrectly, a public key is copied incompletely, quote handling breaks the value, or a human edits the record by hand instead of pasting the provider-generated string exactly.
Why this is a problem
- Receivers cannot parse the DKIM key correctly.
- DKIM verification fails even when the sender is legitimate.
- DMARC may fail if DKIM was expected to provide aligned authentication.
- Troubleshooting becomes confusing because the selector exists but still does not work.
How this affects deliverability
An invalid DKIM key creates one of the most frustrating deliverability issues because the record exists, but it still fails verification. Mailbox providers do not reward the intent to configure DKIM. They reward a technically valid, stable implementation.
Common causes
- The public key was truncated during copy-paste.
- A DNS provider handled long TXT values incorrectly.
- Quotes or spaces were added in the wrong place.
- A human edited the key instead of pasting the exact provider-generated value.
What we checked
We reviewed whether the published DKIM TXT record contains a valid, parseable public key and whether the record format is consistent with a working DKIM selector.
Live DNS lookup. No login. No saved domains. No tracking.
FAQ
Can a selector exist but still be invalid?
Yes. The selector hostname may exist in DNS, but if the key itself is malformed or incomplete, DKIM verification still fails.
Should I ever edit the DKIM key manually?
No. Use the exact DKIM value generated by the sending provider unless their documentation explicitly says otherwise.
Can TXT record splitting break DKIM?
Yes. Some DNS tools support long TXT values safely, but bad formatting or truncation can still corrupt the published key.
Next steps
- Copy the DKIM public key again from the actual sending provider.
- Replace the existing DNS value without manual edits.
- Confirm the selector hostname is correct.
- Wait for DNS propagation.
- Send a fresh test email and verify DKIM now passes.
- Review the full troubleshooting guidance in the DKIM Hub.
- Explore sender authorization issues in the SPF Hub.
- Review alignment and policy issues in the DMARC Hub.