SPF, which abbreviates Sender Policy Framework, is a certification system that aims at stopping the so-called email counterfeiting. Basically, this means sending some message from one e-mail and making it appear to be sent from another one with the purpose to scam in some manner the person receiving it. If the SPF protection is activated for a domain name, a record which includes all mail servers authorized to send messages with addresses under the domain is generated. The record is kept on all of the DNS servers that route the Internet traffic worldwide, so they all can identify if an e-mail message originates from a trustworthy server or not. The verification is done at the first server where the email goes through and in the first case the e-mail message is forwarded, but in the second it is discarded and it never gets to its intended recipient. Applying SPF records for your domains will prevent any unwanted people from using your email addresses for harmful objectives.