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The Sender Policy Framework (SPF) is a technology-based email-authentication technique. It is used to stop spammers from sending messages on behalf of your domain. It is with the use of SPF records, an organization can publish authorized mail servers. 

It is an email authentication technique that uses DNS (Domain Name Service). As an email sender, it provides you, the ability to state which email servers are permitted to send emails on behalf of your business domain.https://godmarc.com/blogs/spf-the-important-pillar-of-email-authentication/