SPF, which means Sender Policy Framework, is an e-mail safety system, that is employed to confirm whether an email message is sent by a certified server. Using SPF protection for a domain will stop the faking of emails generated with the domain. In simple words: enabling this function for a domain makes a specific record in the Domain Name System (DNS) that contains the IP of the servers that are allowed to send e-mail messages from mailboxes under the domain. When this record propagates globally, it exists on all the DNS servers that direct the Internet traffic. Any time an e-mail message is sent, the initial DNS server it goes through tests whether it comes from an authorized server. If it does, it's sent to the destination address, but if it doesn't come from a server indexed in the SPF record for the particular domain, it's rejected. Thus nobody will be able to mask an e-mail address and make it appear as if you are sending spam. This technique is also termed email spoofing.