SPF, which is an abbreviation for Sender Policy Framework, is an authentication system that aims at blocking the so-called e-mail faking. Essentially, this indicates sending a message from one e-mail and making it look like it’s sent from another with the objective to scam in some manner the person opening it. If the SPF protection is active for a domain, a record that includes all the mail servers authorized to send messages with addresses part of the domain is made. The record is saved on all of the DNS servers that direct the web traffic all over the world, therefore they all will recognize if an email message comes from a trustworthy server or not. The check is conducted at the first server where the email goes through and in the first case the email message is forwarded, whereas in the second one it is discarded and it never gets to the intended recipient. Applying SPF records for your domains will prevent any unauthorized people from using your email addresses for harmful purposes.