SPF, which stands for Sender Policy Framework, is an e-mail protection system, which is designed to confirm if an email message was sent by a certified server. Employing SPF protection for a given domain will stop the counterfeiting of emails generated with the domain. In layman's terms: activating this attribute for a domain name creates a specific record in the Domain Name System (DNS) which contains the IP of the servers that are allowed to send emails from mailboxes using the domain. The moment this record propagates worldwide, it exists on all the DNS servers that route the Internet traffic. Any time an e-mail message is sent, the initial DNS server it goes through verifies whether it originates from an authorized server. If it does, it's sent to the destination address, however when it doesn't come from a server part of the SPF record for the domain, it is discarded. Thus nobody will mask an email address then make it appear as if you are sending spam messages. This approach is also referred to as email spoofing.