SPF, which is an abbreviation for Sender Policy Framework, is a certification system that aims at preventing the so-called e-mail faking. Essentially, this indicates sending some message from one e-mail address and making it appear to be sent from a different one with the objective to scam in some manner the person getting it. In the event that the SPF protection is running for a domain, a record which contains all of the mail servers authorized to send messages with addresses within the domain is created. The record is placed on all of the DNS servers that route the web traffic all over the world, thus they all can identify whether an email message comes from an authentic server or not. The check is conducted at the very first server where the e-mail goes through and in the first case the email message is forwarded, and in the second it's discarded and it never reaches the intended recipient. Applying SPF records for your domain names will prevent any unauthorized people from making use of your emails for malicious objectives.