SPF, which is short for Sender Policy Framework, is an email protection system, which is is intended to verify if an email message is sent by an official server. Using SPF protection for a particular domain name will stop the forging of emails generated with the domain. In layman's terms: enabling this attribute for a domain name makes a special record in the Domain Name System (DNS) containing the IP of the servers that are allowed to send e-mails from mailboxes under the domain. Once this record propagates worldwide, it will exist on all of the DNS servers that route the Internet traffic. Whenever a new email message is sent, the first DNS server it uses tests if it originates from an official server. If it does, it's forwarded to the destination address, however when it does not come from a server listed in the SPF record for the domain, it's rejected. Thus nobody will mask an e-mail address to make it look as if you are e-mailing spam. This approach is also called email spoofing.