SPF, which means Sender Policy Framework, is an email security system, which is designed to validate if an email message was sent by an official server. Using SPF protection for a domain name will prevent the counterfeiting of email addresses made with the domain. In simple words: activating this function for a domain creates a specific record in the Domain Name System (DNS) which contains the IP addresses of the servers that are permitted to send e-mail messages from mail boxes using the domain. The moment this record propagates worldwide, it exists on all DNS servers that route the Internet traffic. When an e-mail message is sent, the first DNS server it goes through verifies if it originates from an accredited server. If it does, it's sent to the destination address, but when it does not come from a server part of the SPF record for the particular domain, it's rejected. In this way nobody will be able to mask an e-mail address then make it appear as if you're e-mailing spam messages. This method is also called email spoofing.