SPF, which is short for Sender Policy Framework, is an e-mail protection system, which is is intended to confirm if an e-mail message is sent by an official server. Using SPF protection for a given domain will prevent the forging of email addresses made with the domain. In layman's terms: enabling this feature for a domain makes a particular record in the Domain Name System (DNS) that contains the IP addresses of the servers which are allowed to send e-mail messages from mail boxes using the domain. The moment this record propagates globally, it exists on all DNS servers that direct the Internet traffic. Every time an e-mail message is sent, the first DNS server it goes through tests if it comes from an official server. If it does, it is sent to the destination address, but when it does not originate from a server indexed in the SPF record for the domain, it is discarded. Thus nobody will mask an e-mail address then make it appear as if you're e-mailing spam. This technique is also called email spoofing.