SPF, which means Sender Policy Framework, is an email security system, which is designed to confirm whether an e-mail message was sent by an authorized server. Employing SPF protection for a domain name will stop the counterfeiting of email addresses generated with the domain. In layman's terms: activating this feature for a domain creates a special record in the Domain Name System (DNS) that contains the IP of the servers that are allowed to send e-mails from mail boxes under the domain. As soon as this record propagates worldwide, it exists on all the DNS servers that route the Internet traffic. When a new e-mail message is sent, the initial DNS server it goes through verifies if it comes from an official server. If it does, it is sent to the destination address, but if it does not come from a server indexed in the SPF record for the particular domain, it's discarded. Thus nobody will mask an email address then make it look as if you are distributing spam. This method is also called email spoofing.