Question 1

What is a DKIM selector?

Accepted Answer

A DKIM selector is a string used to locate the DKIM public key in DNS. The full lookup is {selector}._domainkey.{domain}. Common selectors include "google" (Google Workspace), "selector1"/"selector2" (Microsoft 365), "k1" (Mailchimp), and "pm" (Postmark).

Question 2

How do I find my DKIM selector?

Accepted Answer

Check your email provider's documentation, or look at the DKIM-Signature header in a sent email — the "s=" tag contains the selector. You can also use our Email Header Analyzer tool to extract it.

Question 3

What key size should my DKIM key be?

Accepted Answer

At least 2048 bits for RSA keys. 1024-bit keys are considered weak and may not be accepted by all providers. Ed25519 keys are smaller but equally secure.

DKIM Selector Checker