DKIM Selector Strategy
Use DKIM selectors to manage multiple keys, rotate credentials safely, and organize email authentication across services.
What Are DKIM Selectors?
A DKIM selector is a label that identifies which DKIM key to use for verification. It allows you to have multiple DKIM keys per domain.
DNS Record Structure:
[selector]._domainkey.yourdomain.comdefault._domainkey.example.comgoogle._domainkey.example.com2025-01._domainkey.example.comWhy Use Multiple Selectors?
Key Rotation
Switch between keys smoothly without downtime during rotation.
Service Separation
Different keys for Google Workspace vs SendGrid vs Salesforce.
Testing
Test new keys before switching production traffic.
Environment Split
Separate keys for staging vs production environments.
Selector Naming Best Practices
Recommended Patterns:
2025-01, 2025-07 (rotation tracking)google, sendgrid, salesforcev1, v2, v3prod, stagingUse lowercase letters, numbers, and hyphens only. Avoid special characters. Max 63 characters.
Key Rotation Strategy
Use selectors to rotate DKIM keys without email delivery interruption.
Zero-Downtime Rotation Process:
2025-01._domainkey.example.comBoth old and new keys are now active
New emails signed with new key
Allow in-flight emails to be verified
Complete migration to new key