SPF, which means Sender Policy Framework, is an email safety system, that is is intended to validate whether an email message was sent by an authorized server. Employing SPF protection for a particular domain will stop the forging of emails made with the domain. In simple words: activating this function for a domain name generates a special record in the Domain Name System (DNS) which includes the IP of the servers that are allowed to send emails from mailboxes using the domain. Once this record propagates worldwide, it exists on all of the DNS servers that route the Internet traffic. Whenever some e-mail message is sent, the first DNS server it goes through checks if it comes from an accredited server. When it does, it's sent to the destination address, however if it doesn't come from a server part of the SPF record for the particular domain, it's discarded. In this way nobody will be able to mask an email address then make it look as if you are sending spam messages. This approach is also called email spoofing.