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Email Security Check / DKIM record checker

DKIM record checker

Finds DKIM public keys on 50 common selectors, or on the selector you enter, and checks the key size. Keys under 1024 bits are flagged as crackable.

DKIM selector (optional)

We test 50 common selectors. If your provider uses its own, find s= in the DKIM-Signature header of an email you sent and enter it here.

Where to find your DKIM selector

  1. Send an email from your domain to any other mailbox you own.
  2. Open it and choose Show original (Gmail), View source (Outlook, Apple Mail).
  3. Find the line starting with DKIM-Signature:. The selector is the value after s=, and d= is the domain.

Common selectors: google (Google Workspace), selector1 and selector2 (Microsoft 365), k1 (Mailchimp), s1 and s2 (SendGrid), fm1 (Fastmail).

Frequently asked questions

What DKIM key length should I use?

2048-bit RSA. 1024-bit still works but is weaker, and keys under 1024 bits can be broken. Some providers also support Ed25519.

What does an empty p= mean?

An empty p= tag means the key was revoked on purpose. Mail signed with that selector will fail DKIM.

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