SPF, which means Sender Policy Framework, is an email security system, that is designed to verify if an e-mail message is sent by a certified server. Employing SPF protection for a particular domain will prevent the counterfeiting of email addresses generated with the domain. In simple words: enabling this function for a domain name creates a particular record in the Domain Name System (DNS) containing the IP of the servers which are permitted to send e-mails from mailboxes under the domain. When this record propagates worldwide, it exists on all of the DNS servers that route the Internet traffic. Any time some e-mail message is sent, the first DNS server it goes through verifies if it comes from an official server. If it does, it's forwarded to the destination address, yet if it doesn't originate from a server part of the SPF record for the domain, it is rejected. In this way nobody will be able to mask an e-mail address to make it look as if you're e-mailing spam. This method is also termed email spoofing.