SPF, which stands for Sender Policy Framework, is an e-mail security system, which is designed to confirm if an email message was sent by a licensed server. Employing SPF protection for a given domain name will prevent the forging of emails created with the domain. In simple words: activating this feature for a domain generates a particular record in the Domain Name System (DNS) which includes the IP addresses of the servers which are permitted to send e-mail messages from mail boxes under the domain. Once this record propagates globally, it will exist on all the DNS servers that route the Internet traffic. Every time a new email message is sent, the initial DNS server it uses tests if it comes from an approved server. In the event it does, it is forwarded to the destination address, however when it does not come from a server part of the SPF record for the particular domain, it is rejected. In this way nobody can mask an email address to make it appear as if you are distributing spam. This approach is also known as email spoofing.