SPF, which stands for Sender Policy Framework, is an email security system, which is employed to validate whether an e-mail message was sent by an authorized server. Employing SPF protection for a domain name will stop the counterfeiting of emails generated with the domain. In simple words: enabling this attribute for a domain name makes a specific record in the Domain Name System (DNS) that contains the IP of the servers that 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 direct the Internet traffic. Any time an e-mail message is sent, the initial DNS server it goes through tests if it originates from an approved server. If it does, it's forwarded to the destination address, however if it does not come from a server part of the SPF record for the domain, it is rejected. In this way nobody will be able to mask an e-mail address to make it appear as if you are distributing spam messages. This technique is also known as email spoofing.