SPF, which is an abbreviation for Sender Policy Framework, is a certification system that is aimed at stopping the so-called e-mail faking. Basically, this means sending some message from one e-mail and making it seem to be sent from a different one with the objective to scam in some manner the individual receiving it. In case the SPF protection is active for a domain, a record that contains all of the mail servers authorized to email messages with addresses within the domain is generated. The record is kept on all of the DNS servers that route the web traffic around the world, so that they all will recognize if an email message comes from an authentic server or not. The verification is done at the very first server where the e-mail goes through and in the first case the e-mail message is forwarded, but in the second it is removed and it never gets to the intended recipient. Applying SPF records for your domains will prevent any unwanted people from making use of your emails for malicious objectives.