SPF, which is an acronym for Sender Policy Framework, is an e-mail security system, that is employed to verify if an e-mail message is sent by a certified server. Employing SPF protection for a particular domain will stop the counterfeiting of email addresses created with the domain. In layman's terms: enabling this function for a domain generates a special record in the Domain Name System (DNS) containing the IP addresses of the servers which are permitted to send e-mails from mailboxes under the domain. The moment this record propagates globally, it exists on all the DNS servers that direct the Internet traffic. Any time a new email message is sent, the first DNS server it goes through tests if it comes from an approved server. When it does, it's sent to the destination address, however if it does not come from a server listed in the SPF record for the particular domain, it's discarded. In this way nobody will mask an e-mail address then make it appear as if you are distributing spam. This technique is also termed email spoofing.