SPF, which means Sender Policy Framework, is an email protection system, that is is intended to validate whether an email message was sent by a certified server. Employing SPF protection for a domain will prevent the forging of emails generated with the domain. In layman's terms: activating this attribute for a domain creates a special record in the Domain Name System (DNS) that contains the IP addresses of the servers which are allowed to send e-mails from mail boxes using the domain. When this record propagates globally, it exists on all the DNS servers that route the Internet traffic. Any time an email message is sent, the initial DNS server it uses tests whether it comes from an authorized server. In the event it does, it is sent to the destination address, yet if it doesn't come from a server indexed in the SPF record for the domain, it's rejected. In this way nobody can mask an email address and make it look as if you're distributing spam. This approach is also called email spoofing.