SPF, which is an abbreviation for Sender Policy Framework, is a validation system that aims at stopping the so-called email counterfeiting. In simple terms, this means sending some message from one e-mail address and making it appear to be sent from a different one with the idea to scam in some manner the person receiving it. If the SPF protection is active for a domain name, a record which contains all the mail servers authorized to email messages with addresses part of the domain is generated. The record is stored on all the DNS servers that direct the Internet traffic across the globe, thus they all can recognize whether an e-mail message originates 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 e-mail message is forwarded, but in the second one it is removed and it never gets to the intended recipient. Employing SPF records for your domains will prevent any unwanted people from making use of your emails for harmful purposes.