SPF, which stands for Sender Policy Framework, is an email security system, that is employed to validate whether an e-mail message is sent by a licensed server. Using SPF protection for a particular domain will stop the forging of emails generated with the domain. In layman's terms: enabling this function for a domain creates a specific record in the Domain Name System (DNS) that contains the IP of the servers that are allowed to send emails from mailboxes using the domain. When this record propagates worldwide, it will exist on all of the DNS servers that direct the Internet traffic. Every time a new e-mail message is sent, the initial DNS server it goes through verifies if it comes from an accredited server. When it does, it is sent to the destination address, but when it does not originate from a server listed in the SPF record for the domain, it is discarded. In this way nobody will mask an email address and make it appear as if you're sending spam. This method is also referred to as email spoofing.