SPF, which is an abbreviation for Sender Policy Framework, is a verification system that is aimed at protecting against the so-called email forging. In simple terms, it indicates sending some message from one email and making it look like it’s sent from another with the purpose to scam in some way the individual getting it. In case the SPF protection is running for a domain name, a record that contains all mail servers authorized to send messages with addresses in the domain is made. The record is stored on all DNS servers that route the Internet traffic around the world, so they all will recognize whether an e-mail message originates from a valid server or not. The verification is conducted at the first server where the email goes through and in the first case the e-mail message is forwarded, whereas in the second one it's removed and it never gets to its intended recipient. Using SPF records for your domain names will prevent any unauthorized people from using your email addresses for harmful objectives.