SPF, which means Sender Policy Framework, is an email safety system, that is designed to validate whether an e-mail message was sent by an official server. Using SPF protection for a particular domain name will prevent the forging of emails created with the domain. In layman's terms: enabling this feature for a domain makes a special record in the Domain Name System (DNS) which contains the IP addresses of the servers which are allowed to send email messages from mailboxes under the domain. As soon as this record propagates worldwide, it will exist on all of the DNS servers that direct the Internet traffic. Any time a new e-mail message is sent, the initial DNS server it uses tests whether it comes from an accredited server. If it does, it's forwarded to the destination address, however when it does not come from a server listed in the SPF record for the particular domain, it's discarded. In this way nobody will mask an e-mail address and make it appear as if you are sending spam. This technique is also referred to as email spoofing.