SPF, which means Sender Policy Framework, is an e-mail security system, that is designed to verify if an e-mail message was sent by an authorized server. Employing SPF protection for a domain name will prevent the forging of emails made with the domain. In layman's terms: activating this attribute for a domain name creates a specific record in the Domain Name System (DNS) containing the IP of the servers that are permitted to send emails from mailboxes under the domain. Once this record propagates worldwide, it will exist on all DNS servers that route the Internet traffic. Whenever an email message is sent, the initial DNS server it uses verifies whether it comes from an accredited server. In the event it does, it is sent to the destination address, but when it doesn't originate from a server listed in the SPF record for the particular domain, it is discarded. Thus nobody will mask an email address then make it appear as if you're distributing spam. This technique is also termed email spoofing.