SPF, which abbreviates Sender Policy Framework, is an authentication system that is aimed at stopping the so-called email faking. Essentially, this means sending some message from one e-mail address and making it seem to be sent from a different one with the objective to scam in some way the person opening it. If the SPF protection is activated for a domain name, a record which contains all of the mail servers authorized to email messages with addresses part of the domain is created. The record is stored on all DNS servers that route the web traffic globally, so that they all will identify if an e-mail message comes from a trustworthy server or not. The verification is conducted at the first server where the email goes through and in the first case the message is forwarded, and in the second it is discarded and it never reaches the intended recipient. Using SPF records for your domains will stop all unauthorized people from using your emails for harmful purposes.