SPF, which abbreviates Sender Policy Framework, is a certification system that aims at preventing the so-called email forging. In simple terms, it indicates sending a message from one email and making it appear to be sent from another with the objective to scam in some manner the person getting it. In case the SPF protection is activated for a domain, a record which includes all mail servers authorized to send messages with addresses part of the domain is created. The record is placed on all of the DNS servers that direct the web traffic globally, therefore they all can identify if an email message originates from an authentic server or not. The verification is done at the first server where the email goes through and in the first case the message is forwarded, but in the second it's removed and it never gets to the intended recipient. Employing SPF records for your domains will stop any unauthorized people from making use of your emails for harmful purposes.