DKIM Lookup
DKIM Lookup
Scans 39 common selectors in parallel and shows all DKIM keys found for the domain.
Enter a domain to scan all common DKIM selectors at once
About this tool
- What is DKIM?
- DomainKeys Identified Mail. A digital signature added to outgoing email that lets receiving servers verify the message was sent by an authorized server and wasn't altered in transit.
- What is a DKIM selector?
- A label that identifies which public key to use for verification. It appears as a subdomain prefix in the DNS lookup (e.g. google._domainkey.example.com). A domain can have multiple selectors — one per sending service.
- Why does DKIM fail?
- Common causes: the email was modified in transit (e.g. by a mailing list or forwarding service), the selector no longer matches the signing key, or the public key in DNS has been rotated without updating the signing configuration.
- What key length should I use?
- 2048-bit RSA keys are the current standard. 1024-bit keys are deprecated and flagged by most mail security tools. Some providers use Ed25519, which is shorter but equally secure.