SPF, which is an abbreviation for Sender Policy Framework, is a certification system that aims at blocking the so-called email counterfeiting. Basically, this means sending a message from one email and making it seem to be sent from another with the objective to scam in some way the individual receiving it. When the SPF protection is activated for a domain, a record which has all mail servers authorized to send messages with addresses within the domain is generated. The record is saved on all the DNS servers that route the Internet traffic internationally, therefore they all will identify if an email message originates from a legitimate server or not. The verification is conducted at the very first server where the email goes through and in the first case the email message is forwarded, while in the second it is discarded and it never reaches the intended recipient. Employing SPF records for your domains will prevent any unauthorized people from using your email addresses for harmful purposes.