SPF, which abbreviates Sender Policy Framework, is a validation system that is aimed at stopping the so-called email counterfeiting. In simple terms, it indicates sending some message from one e-mail address and making it seem to be sent from another one with the objective to scam in some manner the individual receiving it. When the SPF protection is active for a domain, a record that contains all mail servers authorized to email messages with addresses under the domain is made. The record is kept on all the DNS servers that direct the Internet traffic worldwide, therefore they all can identify if an e-mail message originates from a trustworthy server or not. The verification is conducted at the very first server where the e-mail goes through and in the first case the message is forwarded, but in the second one it's discarded and it never reaches the supposed recipient. Using SPF records for your domains will stop all unauthorized people from using your email addresses for harmful objectives.