DKIM Checker & Lookup
Run a free DKIM lookup to validate your domain's DKIM record and verify email signing.
Check DKIM Without Knowing Your Selector
Most DKIM checkers make you enter a selector before they can look anything up — but many people don't know theirs. Our checker's auto-scan tries the selectors used by popular email providers automatically, so you can test your domain with nothing but the domain name. If you do know your selector (from the s= tag in a DKIM-Signature header), enter it for a direct lookup of selector._domainkey.yourdomain.com.
Common DKIM Selectors by Provider
| Provider | Typical selectors |
|---|---|
| Google Workspace / Gmail | |
| Microsoft 365 | selector1, selector2 |
| Mailchimp / Mandrill | k1, k2, k3, mandrill |
| SendGrid | s1, s2 |
| Postmark | pm |
| Proton Mail | protonmail, protonmail2, protonmail3 |
| Amazon SES | Three unique selectors generated per domain (shown in the SES console) |
A domain can publish several DKIM keys at once — one per sending service — and that's good practice. Each service signs with its own selector, and receivers verify whichever signature is present. After confirming your DKIM record, make sure DMARC ties it together: run a DMARC lookup to verify alignment.
DKIM Checker FAQs
What is a DKIM record?
DKIM (DomainKeys Identified Mail) is an email authentication method that uses cryptographic signatures. The sending server signs each email with a private key, and the public key is published as a DNS TXT record so receivers can verify the signature.
What is a DKIM selector?
A DKIM selector is a string that identifies which DKIM key pair to use. The full DNS name is selector._domainkey.yourdomain.com. Common selectors include "google" for Google Workspace, "selector1" for Microsoft 365, and "k1" for Mailchimp.
How do I find my DKIM selector?
Check your email provider's documentation, look at the DKIM-Signature header in a sent email (the "s=" value), or use our "Try Common Selectors" auto-scan feature to detect it automatically.
Can I check DKIM without knowing my selector?
Yes. Enter just your domain and use the auto-scan, which tries the common selectors from major providers (google, selector1, selector2, k1, s1, and more) and reports any DKIM records it finds.
What key length should I use for DKIM?
Use at least 2048-bit RSA keys. While 1024-bit keys still work, they are considered weak by modern standards. Some providers now support Ed25519 keys, which offer strong security with shorter key sizes.
How does DKIM relate to DMARC?
DMARC uses DKIM (and SPF) for email authentication. For DMARC to pass via DKIM, the domain in the DKIM signature must align with the "From" domain. Check your DMARC record to see your alignment settings.
Related Tools
DMARC Checker
Validate your domain's DMARC record and security posture.
SPF Checker
Look up and validate SPF records with DNS lookup analysis.
Create DMARC Record
Build a custom DMARC record with step-by-step guidance.
Bulk DMARC & SPF Lookup
Validate DMARC and SPF records for up to 50 domains at once.
DMARC Analyzer
Upload and parse DMARC XML aggregate reports.