What Is a DKIM Selector?
A DKIM selector is a string used to locate the correct DKIM public key in DNS. It allows a domain to have multiple DKIM key pairs — one for each email service or for key rotation purposes.
How DKIM Selectors Work
When a sending server signs an email with DKIM, it includes the selector in the DKIM-Signature header as the s= tag. The receiving server uses this selector to construct the DNS query: selector._domainkey.yourdomain.com. The TXT record at that location contains the public key used to verify the signature.
Common DKIM Selectors
Each email provider uses its own selector convention. Google Workspace uses google. Microsoft 365 uses selector1 and selector2. Mailchimp uses k1. Amazon SES uses s1 and s2. Our DKIM Selector Finder scans 30+ common selectors automatically.
Key Rotation with Selectors
Selectors enable seamless DKIM key rotation. You publish a new key under a new selector, switch your signing configuration, and remove the old key after a transition period. During the transition, both old and new keys work because they use different selectors.
Frequently Asked Questions
Where do I find my DKIM selector?
Check your email provider's documentation for the selector name. You can also inspect the s= tag in the DKIM-Signature header of any email sent from your domain.
Can I have multiple DKIM selectors?
Yes. Each email service can have its own selector and key pair. There is no limit on the number of DKIM selectors per domain.
How do I rotate DKIM selectors?
Create a new selector with a new key pair, publish the public key in DNS, switch your mail server to sign with the new selector, and remove the old DNS record after a transition period.