SPF, which means Sender Policy Framework, is an email security system, which is employed to verify if an e-mail message is sent by an official server. Employing SPF protection for a given domain name will stop the forging of emails created with the domain. In simple words: activating this function for a domain name creates a special record in the Domain Name System (DNS) that contains the IP of the servers which are permitted to send e-mail messages from mail boxes using the domain. As soon as this record propagates worldwide, it exists on all the DNS servers that route the Internet traffic. Whenever some email message is sent, the first DNS server it goes through tests if it originates from an authorized server. In the event it does, it's forwarded to the destination address, but when it doesn't come from a server listed in the SPF record for the domain, it's discarded. In this way nobody will be able to mask an e-mail address then make it appear as if you're e-mailing spam messages. This method is also known as email spoofing.