SPF, which abbreviates Sender Policy Framework, is a validation system that is aimed at stopping the so-called email faking. Essentially, it indicates sending a message from one email and making it seem to be sent from another one with the objective to scam in some manner the person receiving it. If the SPF protection is activated for a domain, a record which contains all the mail servers authorized to send messages with addresses under the domain is made. The record is saved on all the DNS servers that direct the web traffic across the globe, thus they all can recognize if an e-mail message comes from an authentic server or not. The verification is performed at the very first server where the e-mail goes through and in the first case the email message is forwarded, whereas in the second it's discarded and it never gets to the intended recipient. Applying SPF records for your domains will stop any unwanted people from making use of your email addresses for malicious purposes.
