SPF, which abbreviates Sender Policy Framework, is a verification system that aims at blocking the so-called e-mail faking. In simple terms, it indicates sending some message from one e-mail and making it look like it’s sent from another with the idea to scam in some manner the person getting it. When the SPF protection is running for a domain name, a record which has all mail servers authorized to send messages with addresses part of the domain is created. The record is saved on all of the DNS servers that direct the Internet traffic internationally, so they all can identify if an e-mail message originates from a trustworthy server or not. The check is done at the very first server where the email goes through and in the first case the message is forwarded, but in the second one it is discarded and it never reaches the supposed recipient. Using SPF records for your domain names will stop any unwanted people from making use of your emails for malicious purposes.