SPF, which is short for Sender Policy Framework, is an e-mail protection system, which is used to validate whether an e-mail message was sent by an official server. Employing SPF protection for a particular domain will prevent the forging of emails made with the domain. In layman's terms: activating this function for a domain name generates a special record in the Domain Name System (DNS) containing the IP of the servers that are allowed to send emails from mail boxes under the domain. The moment this record propagates globally, it will exist on all DNS servers that route the Internet traffic. Every time a new email message is sent, the first DNS server it goes through verifies if it originates from an authorized server. When it does, it's forwarded to the destination address, however if it does not come from a server listed in the SPF record for the domain, it is rejected. In this way nobody will mask an email address and make it look as if you're e-mailing spam messages. This method is also referred to as email spoofing.