DKIM configuration involves generating a pair of cryptographic keys: a private key to sign your emails and a public key to publish in your DNS records. The steps are as follows:
Generate the key pair in your email service provider's settings. Add the public key as a TXT record in your DNS settings. Enable DKIM signing in your email service provider's settings.
For example, a DKIM TXT record might look like this:
selector._domainkey.example.com IN TXT "v=DKIM1; k=rsa; p=public_key"