SPF, which is an abbreviation for Sender Policy Framework, is a verification system that aims at blocking the so-called email faking. In simple terms, it indicates sending some message from one email address and making it look like it’s sent from a different one with the idea to scam in some manner the individual opening it. If the SPF protection is activated for a domain name, a record which includes all the mail servers authorized to send messages with addresses under the domain is made. The record is kept on all of the DNS servers that direct the Internet traffic all over the world, so that they all will identify whether an email message originates from a legitimate server or not. The check is conducted at the first server where the e-mail goes through and in the first case the message is forwarded, whereas in the second it's discarded and it never gets to its intended recipient. Applying SPF records for your domain names will stop all unauthorized people from using your emails for malicious purposes.