SPF, which is an acronym for Sender Policy Framework, is an email security system, which is used to validate whether an e-mail message is sent by a certified server. Using SPF protection for a given domain name will stop the forging of emails generated with the domain. In layman's terms: activating this attribute for a domain name generates a specific record in the Domain Name System (DNS) containing the IP of the servers which are permitted to send e-mail messages from mail boxes using the domain. When this record propagates worldwide, it will exist on all the DNS servers that route the Internet traffic. Whenever some email message is sent, the initial DNS server it uses tests whether it originates from an authorized server. When it does, it is sent to the destination address, yet if it doesn't originate from a server indexed in the SPF record for the domain, it's discarded. In this way nobody will mask an email address and make it appear as if you're distributing spam messages. This technique is also known as email spoofing.