SPF, which is an acronym for Sender Policy Framework, is an email security system, that is used to confirm if an email message is sent by an authorized server. Employing SPF protection for a given domain name will prevent the faking of email addresses created with the domain. In simple words: enabling this feature for a domain name makes a particular record in the Domain Name System (DNS) containing the IP of the servers which are permitted to send emails from mailboxes using the domain. Once this record propagates worldwide, it exists on all of the DNS servers that direct the Internet traffic. Whenever a new email message is sent, the initial DNS server it goes through verifies whether it originates from an approved server. If it does, it's forwarded to the destination address, but when it doesn't originate from a server listed in the SPF record for the particular domain, it is rejected. Thus nobody will mask an e-mail address and make it appear as if you're distributing spam. This technique is also identified as email spoofing.