SPF, which is an acronym for Sender Policy Framework, is an e-mail security system, which is designed to validate whether an email message was sent by a licensed server. Using SPF protection for a given domain name will prevent the forging of emails generated with the domain. In layman's terms: activating this attribute for a domain name creates a special record in the Domain Name System (DNS) that contains the IP addresses of the servers which are permitted to send e-mail messages from mail boxes using the domain. As soon as this record propagates globally, it will exist on all of the DNS servers that direct the Internet traffic. Any time some e-mail message is sent, the first DNS server it goes through verifies if it comes from an accredited server. In the event it does, it's forwarded to the destination address, yet when it doesn't come from a server part of the SPF record for the domain, it's rejected. In this way nobody will be able to mask an e-mail address to make it look as if you are distributing spam messages. This method is also known as email spoofing.