Identify all the servers that send emails on behalf of your domain. Create an SPF record that includes these servers. The record will look something like this: v=spf1 include:_spf.google.com ~all Publish the SPF record in your domain's DNS settings.
Implementing DKIM
Generate a DKIM key pair (public and private keys). Publish the public key in your domain's DNS settings. Configure your email server to sign outgoing emails with the private key.
Implementing DMARC
Create a DMARC policy. The policy will look something like this: v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com Publish the DMARC policy in your domain's DNS settings.