SPF, which abbreviates Sender Policy Framework, is a validation system that is aimed at protecting against the so-called e-mail forging. In simple terms, this means sending some message from one email and making it appear to be sent from a different one with the objective to scam in some way the person opening it. If the SPF protection is active for a domain, a record that contains all the mail servers authorized to send messages with addresses part of the domain is generated. The record is saved on all DNS servers that direct the web traffic globally, thus they all can identify if an email message originates from an authentic server or not. The verification is conducted at the very first server where the email goes through and in the first case the email message is forwarded, but in the second it is discarded and it never gets to the supposed recipient. Applying SPF records for your domain names will stop all unwanted people from making use of your email addresses for harmful purposes.