SPF, which is an abbreviation for Sender Policy Framework, is an authentication system that is aimed at protecting against the so-called email counterfeiting. In simple terms, this indicates sending some message from one e-mail and making it appear to be sent from another one with the objective to scam in some manner the person getting it. In the event that the SPF protection is active for a domain, a record which contains all the mail servers authorized to email messages with addresses under the domain is made. The record is stored on all the DNS servers that direct the web traffic around the world, therefore they all will recognize whether an email message comes from a legitimate server or not. The verification is conducted at the very first server where the email goes through and in the first case the e-mail message is forwarded, and in the second one it is discarded and it never reaches its intended recipient. Using SPF records for your domains will prevent all unauthorized people from making use of your emails for malicious objectives.