SPF, which is short for Sender Policy Framework, is an email protection system, that is used to validate whether an email message was sent by an official server. Using SPF protection for a particular domain name will stop the counterfeiting of emails created with the domain. In simple words: enabling this attribute for a domain name makes a particular record in the Domain Name System (DNS) containing the IP of the servers that are allowed to send e-mails from mail boxes using the domain. When this record propagates worldwide, it will exist on all the DNS servers that route the Internet traffic. When a new e-mail message is sent, the first DNS server it goes through tests whether it originates from an official server. If it does, it's forwarded to the destination address, yet when it does not originate from a server indexed in the SPF record for the domain, it is discarded. Thus nobody can mask an email address and make it appear as if you are distributing spam messages. This approach is also termed email spoofing.