SPF, which stands for Sender Policy Framework, is an e-mail protection system, that is designed to validate whether an e-mail message was sent by an authorized server. Using SPF protection for a particular domain will stop the counterfeiting of emails generated with the domain. In simple words: enabling this attribute for a domain name makes a specific record in the Domain Name System (DNS) that contains the IP of the servers which are allowed to send email messages from mail boxes using the domain. When this record propagates globally, it exists on all of the DNS servers that route the Internet traffic. When a new e-mail message is sent, the initial DNS server it uses tests whether it comes from an approved server. If it does, it's forwarded to the destination address, yet when it does not come from a server indexed in the SPF record for the domain, it is rejected. Thus nobody will be able to mask an email address then make it appear as if you're e-mailing spam messages. This method is also known as email spoofing.