SPF, which means Sender Policy Framework, is an e-mail protection system, that is is intended to verify if an email message was sent by an authorized server. Using SPF protection for a particular domain will prevent the counterfeiting of emails created with the domain. In layman's terms: enabling this function for a domain makes a particular record in the Domain Name System (DNS) which contains the IP addresses of the servers that are allowed to send emails from mailboxes under the domain. Once this record propagates worldwide, it will exist on all DNS servers that direct the Internet traffic. Any time an email message is sent, the initial DNS server it goes through checks whether it originates from an accredited server. When it does, it is forwarded to the destination address, yet if it doesn't come from a server part of the SPF record for the particular domain, it is rejected. In this way nobody can mask an e-mail address then make it appear as if you are sending spam. This method is also called email spoofing.