SPF, which is short for Sender Policy Framework, is an e-mail protection system, which is used to confirm if an email message was sent by an authorized server. Employing SPF protection for a particular domain name will prevent the forging of email addresses made with the domain. In layman's terms: enabling this attribute for a domain name creates a particular record in the Domain Name System (DNS) which includes the IP addresses of the servers that are allowed to send email messages from mailboxes under the domain. As soon as this record propagates globally, it will exist on all DNS servers that route the Internet traffic. When some email message is sent, the first DNS server it uses verifies if it originates from an authorized server. In the event it does, it's sent to the destination address, yet if it doesn't originate from a server listed in the SPF record for the domain, it is rejected. In this way nobody will be able to mask an email address and make it look as if you are e-mailing spam. This technique is also called email spoofing.