- SPF: Publish an SPF record in your domain's DNS settings. This record lists the IP addresses or hostnames that are authorized to send email on behalf of your domain. - DKIM: Generate a DKIM key pair (public and private keys). Publish the public key in your DNS settings and configure your email server to sign outgoing emails with the private key. - DMARC: Create a DMARC policy and publish it in your DNS settings. Specify how you want email servers to handle emails that fail SPF or DKIM checks.