SPF, which is short for Sender Policy Framework, is an e-mail protection system, which is used to confirm whether an e-mail message is sent by a certified server. Employing SPF protection for a particular domain name will stop the counterfeiting of emails generated with the domain. In layman's terms: activating this feature for a domain name creates a particular record in the Domain Name System (DNS) that contains the IP addresses of the servers that are allowed to send emails from mailboxes using the domain. As soon as this record propagates worldwide, it exists on all of the DNS servers that direct the Internet traffic. Whenever an email message is sent, the initial DNS server it goes through checks if it comes from an authorized server. When it does, it is sent to the destination address, however if it doesn't originate from a server part of the SPF record for the domain, it's rejected. Thus nobody will mask an email address and make it appear as if you're distributing spam messages. This method is also known as email spoofing.