SPF, which means Sender Policy Framework, is an email protection system, that is employed to confirm whether an email message was sent by a licensed server. Using SPF protection for a domain will prevent the counterfeiting of emails made 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 includes the IP addresses of the servers that are allowed to send e-mail messages from mail boxes under the domain. As soon as this record propagates worldwide, it will exist on all DNS servers that route the Internet traffic. Any time some email message is sent, the first DNS server it uses verifies if it comes from an authorized server. In the event it does, it is forwarded to the destination address, but if it doesn't originate from a server part of the SPF record for the domain, it is rejected. Thus nobody can mask an e-mail address then make it appear as if you're distributing spam. This approach is also referred to as email spoofing.