SPF, which stands for Sender Policy Framework, is an email protection system, which is employed to validate if an e-mail message was sent by an official server. Employing SPF protection for a particular domain name will prevent the forging of email addresses made with the domain. In simple words: enabling this feature for a domain generates a specific record in the Domain Name System (DNS) which includes the IP of the servers that are allowed to send e-mail messages from mail boxes under the domain. When this record propagates worldwide, it exists on all of the DNS servers that direct the Internet traffic. Whenever a new e-mail message is sent, the initial DNS server it goes through checks if it originates from an official server. When it does, it's sent to the destination address, yet when it does not come from a server part of the SPF record for the domain, it is rejected. Thus nobody can mask an email address then make it look as if you're distributing spam messages. This method is also referred to as email spoofing.