Question 1

What is DKIM?

Accepted Answer

DKIM (DomainKeys Identified Mail) is an email authentication method that adds a digital signature to your emails. This allows receiving servers to verify the email was sent by an authorized sender and wasn't modified in transit.

Question 2

What is a DKIM selector?

Accepted Answer

A DKIM selector is an identifier that tells receiving servers which public key to use to verify the signature. Common selectors include 'google' for Google Workspace, 'selector1' for Microsoft 365, and 's1' for SendGrid.

Question 3

What key size should I use?

Accepted Answer

2048-bit RSA keys are the current standard and provide strong security. Keys smaller than 1024 bits are considered weak. Some providers now support Ed25519 keys which are smaller but equally secure.

Question 4

How do I find my DKIM selector?

Accepted Answer

Check your email service provider's documentation, or look at the headers of a sent email. The DKIM-Signature header contains 's=' followed by your selector name.

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