DKIM
DomainKeys Identified Mail - an email authentication method adding a digital signature.
1 min readLast updated Apr 2026
Quick Reference
CategoryEmail Marketing & Klaviyo
Related Terms2
DomainKeys Identified Mail - an email authentication method adding a digital signature.
Why It Matters
DKIM adds a cryptographic signature to your emails proving they haven't been tampered with in transit. This builds trust with receiving servers and is essential for DMARC alignment. Gmail and Yahoo now require DKIM authentication for bulk senders.
Practical Example
Scenario
A CPG brand notices their emails show 'mailed-by: klaviyo.com' instead of their domain, and some corporate servers reject them.
Calculation
Without DKIM signing on their domain, emails appear to come from Klaviyo, not their brandResult
After setting up custom DKIM (adding DNS records from Klaviyo), emails show their domain and pass authentication checks. Corporate server delivery improves.
Pro Tips
- 1Set up custom DKIM (branded sending domain) through your ESP—don't use their default shared signing
- 2Use 2048-bit keys for stronger security (1024-bit is minimum, increasingly deprecated)
- 3Rotate DKIM keys periodically (annually) as a security best practice
- 4Verify DKIM is passing by checking email headers in received messages
Common Mistakes to Avoid
Using default ESP signing instead of setting up custom DKIM on your domain
Incorrectly copying DNS records (extra spaces, missing characters cause failures)
Not verifying DKIM is actually passing after setup