SPF, which means Sender Policy Framework, is an email safety system, that is employed to verify if an email message was sent by an official server. Using SPF protection for a particular domain will prevent the forging of email addresses generated with the domain. In simple words: enabling this attribute for a domain creates a special record in the Domain Name System (DNS) which contains the IP addresses of the servers that are permitted to send email messages from mail boxes under the domain. As soon as this record propagates worldwide, it exists on all of the DNS servers that direct the Internet traffic. Any time some email message is sent, the initial DNS server it goes through checks whether it comes from an official server. If it does, it is forwarded to the destination address, yet when it doesn't come from a server listed in the SPF record for the domain, it is discarded. Thus nobody will be able to mask an e-mail address and make it appear as if you're distributing spam. This technique is also known as email spoofing.