SPF, which is an abbreviation for Sender Policy Framework, is a certification system that aims at stopping the so-called e-mail counterfeiting. In simple terms, it indicates sending a message from one email and making it look like it’s sent from another with the purpose to scam in some manner the person getting it. In the event that the SPF protection is activated for a domain, a record which includes all mail servers authorized to email messages with addresses under the domain is made. The record is stored on all DNS servers that direct the web traffic globally, so they all will identify whether an e-mail message comes from an authentic server or not. The check is performed at the first server where the email goes through and in the first case the message is forwarded, and in the second one it's removed and it never reaches the supposed recipient. Employing SPF records for your domain names will prevent all unwanted people from making use of your email addresses for harmful purposes.