SPF, which abbreviates Sender Policy Framework, is a validation system that aims at blocking the so-called email faking. Essentially, it indicates sending some message from one email address and making it look like it’s sent from another one with the objective to scam in some way the person getting it. When the SPF protection is active for a domain name, a record which has all of the mail servers authorized to send messages with addresses within the domain is made. The record is placed on all DNS servers that direct the web traffic across the globe, therefore they all will recognize whether an e-mail message originates from a valid server or not. The verification is conducted at the first server where the email goes through and in the first case the message is forwarded, whereas in the second it's removed and it never reaches the supposed recipient. Using SPF records for your domains will stop all unauthorized people from making use of your emails for harmful objectives.