SPF, which abbreviates Sender Policy Framework, is a verification system that aims at protecting against the so-called email faking. In simple terms, it indicates sending some message from one email and making it seem to be sent from another one with the idea to scam in some manner the individual opening it. In case the SPF protection is active for a domain, a record that includes all mail servers authorized to email messages with addresses under the domain is generated. The record is saved on all the DNS servers that direct the web traffic all over the world, therefore they all can identify if an e-mail message originates from a valid server or not. The check is performed at the first server where the email goes through and in the first case the e-mail message is forwarded, and in the second it's removed and it never reaches its intended recipient. Employing SPF records for your domain names will prevent any unwanted people from making use of your email addresses for malicious purposes.