SPF, which means Sender Policy Framework, is an e-mail security system, that is employed to verify if an e-mail message is sent by a certified server. Using SPF protection for a domain name will stop the forging of emails generated with the domain. In layman's terms: enabling this attribute for a domain creates a specific record in the Domain Name System (DNS) which includes the IP of the servers that are allowed to send email messages from mail boxes using the domain. The moment this record propagates worldwide, it will exist on all the DNS servers that direct the Internet traffic. When some e-mail message is sent, the initial DNS server it goes through verifies whether it comes from an authorized server. When it does, it is forwarded to the destination address, but when it doesn't come from a server indexed in the SPF record for the domain, it is discarded. Thus nobody can mask an e-mail address then make it appear as if you're e-mailing spam. This technique is also termed email spoofing.