SPF, which is short for Sender Policy Framework, is an e-mail security system, that is designed to confirm whether an e-mail message is sent by a certified server. Employing SPF protection for a particular domain will prevent the forging of email addresses generated with the domain. In simple words: activating this feature for a domain generates a specific record in the Domain Name System (DNS) which includes the IP addresses of the servers which are permitted to send email messages from mail boxes using the domain. The moment this record propagates globally, it exists on all of the DNS servers that route the Internet traffic. Every time some e-mail message is sent, the initial DNS server it goes through tests whether it originates from an official server. If it does, it is sent to the destination address, but if it doesn't originate from a server listed in the SPF record for the domain, it's rejected. In this way nobody can mask an e-mail address then make it look as if you are e-mailing spam messages. This method is also identified as email spoofing.