DKIM (DomainKeys Identified Mail)
A cryptographic signature added to emails that proves they came from your domain and weren't tampered with in transit.
What is DKIM (DomainKeys Identified Mail)?
DKIM (DomainKeys Identified Mail) adds a digital signature to every email you send. This signature is created using a private key that only your mail server knows, and receiving servers verify it using a public key published in your DNS.
Think of DKIM like a wax seal on a letter - it proves the email genuinely came from you and hasn't been modified since it was sent. If someone intercepts and changes your email, the DKIM signature will fail verification.
DKIM is typically configured by your email provider (Microsoft 365, Google Workspace) and requires adding specific DNS records (called selectors) to your domain.
Why It Matters
- 1Cryptographically proves emails are legitimately from your domain
- 2Detects if emails were modified in transit
- 3Required for DMARC compliance
- 4Major email providers (Gmail, Microsoft) heavily weight DKIM in spam decisions
How to Measure
Check email headers for "dkim=pass" or use our DNS Validation tool to verify DKIM records are published.
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