SPF, which is short for Sender Policy Framework, is an email protection system, that is used to validate if an email message was sent by a certified server. Employing SPF protection for a particular domain name will stop the counterfeiting of emails made with the domain. In layman's terms: enabling this attribute for a domain makes a particular record in the Domain Name System (DNS) which includes the IP addresses of the servers which are permitted to send e-mails from mail boxes under the domain. When this record propagates globally, it will exist on all DNS servers that direct the Internet traffic. Whenever a new e-mail message is sent, the initial DNS server it uses checks if it comes from an authorized server. When it does, it's forwarded to the destination address, but if it doesn't come from a server part of the SPF record for the domain, it's rejected. Thus nobody will be able to mask an e-mail address to make it appear as if you're distributing spam messages. This method is also called email spoofing.