SPF, which means Sender Policy Framework, is an e-mail safety system, that is designed to confirm whether an email message is sent by an authorized server. Using SPF protection for a given domain name will prevent the forging of email addresses generated with the domain. In simple words: activating this function for a domain generates a specific record in the Domain Name System (DNS) that contains the IP addresses of the servers that are allowed to send e-mail messages from mail boxes under the domain. When this record propagates globally, it exists on all the DNS servers that route the Internet traffic. When some e-mail message is sent, the initial DNS server it uses verifies whether it originates from an authorized server. In the event it does, it is forwarded to the destination address, but when it doesn't originate from a server listed in the SPF record for the domain, it's discarded. In this way nobody will mask an e-mail address to make it appear as if you are sending spam messages. This method is also termed email spoofing.