SPF, which is an acronym for Sender Policy Framework, is an e-mail protection system, that is designed to confirm if an e-mail message is sent by an official server. Using SPF protection for a given domain will stop the forging of email addresses created with the domain. In layman's terms: activating this feature for a domain makes a specific record in the Domain Name System (DNS) containing the IP of the servers that are permitted to send email messages from mail boxes using the domain. The moment this record propagates globally, it exists on all DNS servers that route the Internet traffic. When a new e-mail message is sent, the initial DNS server it uses checks if it originates from an authorized server. In the event it does, it's sent to the destination address, but if it does not come from a server part of the SPF record for the domain, it is rejected. Thus nobody can mask an email address and make it look as if you're sending spam messages. This approach is also known as email spoofing.