SPF, which is an abbreviation for Sender Policy Framework, is a validation system that is aimed at stopping the so-called email faking. Essentially, this means sending a message from one email address and making it appear to be sent from another one with the objective to scam in some way the individual opening it. When the SPF protection is activated for a domain name, a record which includes all the mail servers authorized to send messages with addresses part of the domain is generated. The record is stored on all the DNS servers that direct the web traffic internationally, therefore they all can recognize whether an email message originates from a valid server or not. The verification is performed at the first server where the e-mail goes through and in the first case the message is forwarded, and in the second one it's discarded and it never gets to the intended recipient. Employing SPF records for your domain names will stop all unauthorized people from using your emails for harmful purposes.