SPF, which is an acronym for Sender Policy Framework, is an e-mail security system, that is employed to verify whether an email message was sent by an official server. Employing SPF protection for a domain name will prevent the faking of email addresses made with the domain. In simple words: enabling this attribute for a domain name creates a specific record in the Domain Name System (DNS) which includes the IP of the servers that are allowed to send e-mail messages from mail boxes under the domain. Once this record propagates worldwide, it exists on all DNS servers that direct the Internet traffic. When an e-mail message is sent, the initial DNS server it uses verifies if it originates from an accredited server. When it does, it's forwarded to the destination address, but when it does not originate from a server indexed in the SPF record for the domain, it is rejected. Thus nobody will be able to mask an email address and make it look as if you are distributing spam messages. This technique is also known as email spoofing.