SPF, which is an abbreviation for Sender Policy Framework, is a validation system that aims at protecting against the so-called e-mail faking. Essentially, it indicates sending some message from one e-mail and making it appear to be sent from another with the idea to scam in some manner the individual opening it. If the SPF protection is running for a domain, a record which includes all of the mail servers authorized to email messages with addresses under the domain is made. The record is placed on all the DNS servers that direct the Internet traffic across the globe, so that they all will identify whether an email message originates from a legitimate server or not. The verification is conducted at the very first server where the e-mail goes through and in the first case the email message is forwarded, while in the second one it is removed and it never reaches the intended recipient. Using SPF records for your domains will stop all unauthorized people from making use of your email addresses for malicious purposes.