SPF, which is an acronym for Sender Policy Framework, is an email security system, which is is intended to confirm if an email message is sent by a licensed server. Using SPF protection for a domain name will prevent the forging of email addresses made with the domain. In layman's terms: activating this function for a domain creates a special record in the Domain Name System (DNS) containing the IP of the servers which are allowed to send e-mail messages from mailboxes using the domain. Once this record propagates globally, it exists on all DNS servers that direct the Internet traffic. When a new email message is sent, the first DNS server it goes through checks whether it originates from an approved server. When it does, it is sent to the destination address, yet if it does not come from a server part of the SPF record for the domain, it is discarded. In this way nobody will be able to mask an email address to make it look as if you're distributing spam. This technique is also known as email spoofing.