SPF, which stands for Sender Policy Framework, is an e-mail safety system, that is designed to verify whether an e-mail message was sent by a licensed server. Using SPF protection for a given domain will prevent the counterfeiting of email addresses made with the domain. In layman's terms: enabling this function for a domain makes a particular record in the Domain Name System (DNS) that contains the IP of the servers that are permitted to send emails from mail boxes using the domain. Once this record propagates worldwide, it exists on all DNS servers that route the Internet traffic. Every time an email message is sent, the first DNS server it goes through tests if it comes from an official server. When it does, it's forwarded to the destination address, but if it doesn't originate from a server indexed in the SPF record for the domain, it is rejected. In this way nobody can mask an e-mail address and make it appear as if you are sending spam. This approach is also known as email spoofing.