SPF, which is an abbreviation for Sender Policy Framework, is a validation system that is aimed at preventing the so-called e-mail counterfeiting. Basically, this indicates sending some message from one e-mail and making it appear to be sent from a different one with the purpose to scam in some manner the individual getting it. In the event that the SPF protection is activated for a domain name, a record which includes all the mail servers authorized to email messages with addresses part of the domain is generated. The record is kept on all the DNS servers that direct the web traffic all over the world, thus they all can recognize whether an email 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 message is forwarded, whereas in the second it is removed and it never reaches its intended recipient. Applying SPF records for your domain names will stop all unwanted people from making use of your email addresses for harmful purposes.