SPF, which is an abbreviation for Sender Policy Framework, is a validation system that is aimed at preventing the so-called email forging. Basically, it indicates sending some message from one email address and making it seem to be sent from a different one with the objective to scam in some way the individual getting it. In the event that the SPF protection is activated for a domain, a record which includes all mail servers authorized to send messages with addresses within the domain is created. The record is saved on all the DNS servers that direct the web traffic around the world, so that they all can recognize whether an email message comes from a trustworthy 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, but in the second it is removed and it never reaches its intended recipient. Applying SPF records for your domain names will prevent all unauthorized people from using your email addresses for malicious objectives.