SPF (or Sender Policy Framework) is one of the most commonly used forms of authentication.
SPF sort of functions like a permission slip. Your domain lists servers that are authorized to send on your behalf and recipient email servers check who is sending against that "permission slip".
By implementing SPF, you can enhance the security and integrity of your domain's email communications, build trust with recipients, and reduce the chances of your domain being used for malicious purposes.
Many of the most common email services like Gmail and Yahoo! Mail require your domain to have SPF set up.
Go to the setup guide:
or
Go to the SPF step: