SPF, which is an abbreviation for Sender Policy Framework, is a verification system that is aimed at protecting against the so-called e-mail faking. In simple terms, this means sending a message from one e-mail and making it look like it’s sent from another one with the idea to scam in some manner the individual opening it. In the event that the SPF protection is activated for a domain name, a record which has all mail servers authorized to email messages with addresses under the domain is generated. The record is kept on all DNS servers that direct the web traffic worldwide, so they all can recognize whether an email message originates from an authentic server or not. The check is conducted at the first server where the e-mail goes through and in the first case the email message is forwarded, and in the second one it's removed and it never gets to the intended recipient. Employing SPF records for your domains will prevent all unauthorized people from making use of your email addresses for harmful purposes.