SPF, which is an acronym for Sender Policy Framework, is an e-mail security system, which is employed to validate if an e-mail message is sent by a certified server. Employing SPF protection for a domain will stop the faking of email addresses made with the domain. In simple words: activating this feature for a domain creates a particular record in the Domain Name System (DNS) which contains the IP of the servers which are permitted to send emails from mailboxes under the domain. As soon as this record propagates worldwide, it exists on all DNS servers that route the Internet traffic. Every time a new email message is sent, the first DNS server it uses tests whether it comes from an authorized server. If it does, it is forwarded to the destination address, yet when it doesn't come from a server indexed in the SPF record for the domain, it is discarded. Thus nobody will be able to mask an e-mail address then make it appear as if you are distributing spam messages. This approach is also termed email spoofing.