SPF, which is short for Sender Policy Framework, is an email protection system, that is used to confirm whether an email message is sent by an authorized server. Employing SPF protection for a particular domain name will stop the counterfeiting of email addresses created with the domain. In simple words: enabling this feature for a domain makes a specific record in the Domain Name System (DNS) which includes the IP of the servers that are permitted to send e-mail messages from mailboxes using the domain. As soon as this record propagates globally, it will exist on all DNS servers that route the Internet traffic. Whenever an email message is sent, the initial DNS server it uses tests if it comes from an approved server. In the event it does, it's sent to the destination address, yet if it does not originate from a server part of the SPF record for the particular domain, it's discarded. In this way nobody can mask an e-mail address to make it appear as if you're distributing spam. This approach is also called email spoofing.