SPF, which means Sender Policy Framework, is an e-mail protection system, that is is intended to confirm whether an e-mail message is sent by a certified server. Employing SPF protection for a particular domain name will stop the forging of emails created with the domain. In simple words: enabling this function for a domain creates a special record in the Domain Name System (DNS) which contains the IP of the servers that are allowed to send email messages from mailboxes using the domain. The moment this record propagates globally, it will exist on all the DNS servers that direct the Internet traffic. Any time some email message is sent, the initial DNS server it uses tests whether it originates from an official server. In the event it does, it's sent to the destination address, yet when it doesn't originate from a server listed in the SPF record for the domain, it is rejected. In this way nobody will mask an email address to make it appear as if you're distributing spam. This approach is also known as email spoofing.