SPF, which means Sender Policy Framework, is an e-mail protection system, which is employed to confirm whether an e-mail message is sent by a certified server. Using SPF protection for a domain name will stop the forging of emails made with the domain. In simple words: enabling this function for a domain creates a special record in the Domain Name System (DNS) containing the IP addresses of the servers which are allowed to send emails from mailboxes using the domain. As soon as this record propagates globally, it will exist on all of the DNS servers that direct the Internet traffic. Whenever some e-mail message is sent, the initial DNS server it goes through checks if it comes from an authorized server. If it does, it is forwarded to the destination address, but when it doesn't originate from a server indexed in the SPF record for the domain, it's discarded. In this way nobody will be able to mask an email address and make it look as if you are distributing spam messages. This approach is also termed email spoofing.