SPF, which is an acronym for Sender Policy Framework, is an e-mail security system, that is designed to confirm whether an email message was sent by an official server. Using SPF protection for a particular domain name will prevent the counterfeiting of email addresses created with the domain. In layman's terms: enabling this feature for a domain name creates a particular record in the Domain Name System (DNS) which contains the IP addresses of the servers that are permitted to send email messages from mail boxes under the domain. Once this record propagates globally, it exists on all the DNS servers that direct the Internet traffic. When a new e-mail message is sent, the first DNS server it uses checks if it originates from an approved server. If it does, it's forwarded to the destination address, but when it does not originate from a server listed in the SPF record for the particular domain, it is rejected. Thus nobody can mask an email address and make it appear as if you're e-mailing spam. This method is also referred to as email spoofing.