SPF, which means Sender Policy Framework, is an email protection system, which is used to validate if an email message is sent by a certified server. Employing SPF protection for a domain will prevent the forging of email addresses made with the domain. In layman's terms: activating this function for a domain generates a special record in the Domain Name System (DNS) containing the IP addresses of the servers that are allowed to send e-mails from mailboxes using the domain. As soon as this record propagates worldwide, it will exist on all DNS servers that direct the Internet traffic. Every time a new email message is sent, the first DNS server it uses verifies whether 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 domain, it's rejected. In this way nobody will be able to mask an e-mail address then make it appear as if you are e-mailing spam. This method is also known as email spoofing.