SPF, which is an abbreviation for Sender Policy Framework, is an authentication system that aims at preventing the so-called e-mail faking. In simple terms, this means sending a message from one e-mail and making it look like it’s sent from another one with the purpose to scam in some manner the person getting it. In case the SPF protection is running for a domain, a record that contains all the mail servers authorized to send messages with addresses part of the domain is made. The record is placed on all of the DNS servers that route the web traffic around the world, so they all can recognize if an e-mail message comes from an authentic server or not. The check is done at the very first server where the e-mail goes through and in the first case the message is forwarded, and in the second one it is removed and it never reaches the supposed recipient. Applying SPF records for your domains will prevent any unauthorized people from making use of your emails for malicious objectives.