SPF, which stands for Sender Policy Framework, is an email security system, which is employed to validate whether an email message was sent by an authorized server. Employing SPF protection for a given domain name will stop the forging of emails generated with the domain. In layman's terms: enabling this function for a domain creates a special record in the Domain Name System (DNS) containing the IP of the servers that are allowed to send emails from mailboxes under the domain. As soon as this record propagates worldwide, it exists on all of the DNS servers that direct the Internet traffic. When an e-mail message is sent, the initial DNS server it goes through checks whether it originates from an approved server. If it does, it is sent to the destination address, yet when it does not originate from a server indexed in the SPF record for the domain, it is discarded. In this way nobody will mask an email address then make it look as if you are sending spam messages. This method is also termed email spoofing.
