SPF, which means Sender Policy Framework, is an email security system, that is designed to confirm if an e-mail message was sent by an official server. Employing SPF protection for a given domain will stop the forging of email addresses created with the domain. In layman's terms: enabling this feature for a domain name generates a specific record in the Domain Name System (DNS) which contains the IP of the servers which are permitted to send e-mails from mail boxes using the domain. When this record propagates globally, it exists on all of the DNS servers that route the Internet traffic. Any time some e-mail message is sent, the first DNS server it uses tests whether it comes from an approved server. If it does, it's sent to the destination address, but if it doesn't come from a server listed in the SPF record for the particular domain, it's rejected. In this way nobody will be able to mask an e-mail address then make it appear as if you're sending spam. This method is also called email spoofing.