What is DKIM?
DKIM (DomainKeys Identified Mail) attaches a cryptographic signature to outgoing email so receivers can verify it came from your domain and was not altered in transit.
Why businesses care
DKIM survives email forwarding, which SPF does not, so it is the more dependable half of DMARC for many businesses.
Example
selector1._domainkey.example.com TXT "v=DKIM1; k=rsa; p=MIIBIjANBg…"How to check
DKIM keys live at <selector>._domainkey.<domain>. The selector is provider-specific, so check your email provider’s admin console; the DKIM checker tries common selectors.
How to fix
Enable DKIM signing in your email provider and publish the DNS record it gives you. Use 2048-bit keys.
Common mistakes
- Publishing the key but never enabling signing
- Using 1024-bit keys
- Leaving old selectors published after switching providers
Sources
Check it with DKIM Checker
Look for DKIM public keys at commonly used selectors and check key size indicators. Learn what a “not found” result really means.
Open DKIM Checker