SPF, which abbreviates Sender Policy Framework, is a validation system that is aimed at stopping the so-called email counterfeiting. Essentially, this indicates sending some message from one email and making it seem to be sent from a different one with the idea to scam in some manner the person opening it. If the SPF protection is active for a domain name, a record which contains 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 route the Internet traffic globally, so they all will recognize if an e-mail message comes from a legitimate server or not. The check is performed at the very first server where the email goes through and in the first case the message is forwarded, while in the second one it's removed and it never gets to its intended recipient. Using SPF records for your domains will prevent all unauthorized people from making use of your email addresses for harmful objectives.