SPF, which is short for Sender Policy Framework, is an e-mail security system, which is designed to confirm whether an email message is sent by an official server. Employing SPF protection for a domain will stop the faking of email addresses generated with the domain. In layman's terms: activating this feature for a domain creates a particular record in the Domain Name System (DNS) which includes the IP of the servers that are allowed to send e-mails 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. Any time some email message is sent, the initial DNS server it goes through verifies if it comes from an official server. In the event it does, it is sent to the destination address, yet if it does not originate from a server indexed in the SPF record for the particular domain, it's discarded. In this way nobody will mask an email address then make it look as if you're sending spam. This method is also called email spoofing.