SPF, which stands for Sender Policy Framework, is an email security system, that is used to verify if an email message is sent by a certified server. Employing SPF protection for a domain name will stop the forging of email addresses created 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 permitted to send email messages from mailboxes using the domain. The moment this record propagates globally, it exists on all of the DNS servers that route the Internet traffic. When an email message is sent, the initial DNS server it uses tests if it originates from an authorized server. In the event it does, it's forwarded to the destination address, however if it does not come from a server part of the SPF record for the domain, it's rejected. In this way nobody can mask an e-mail address then make it appear as if you're e-mailing spam messages. This approach is also termed email spoofing.