SPF, which means Sender Policy Framework, is an email protection system, that is employed to verify if an email message is sent by an official server. Employing SPF protection for a given domain will prevent the forging of email addresses made with the domain. In simple words: activating this attribute for a domain makes a specific record in the Domain Name System (DNS) containing the IP of the servers which are allowed to send email messages from mailboxes using the domain. When this record propagates globally, it exists on all of the DNS servers that direct the Internet traffic. Every time some email message is sent, the first DNS server it goes through tests whether it comes from an accredited server. In the event it does, it's forwarded to the destination address, yet when it doesn't originate from a server part of the SPF record for the domain, it is rejected. In this way nobody can mask an email address to make it look as if you are distributing spam messages. This method is also termed email spoofing.