SPF, which means Sender Policy Framework, is an e-mail protection system, which is used to verify whether an e-mail message is sent by an authorized server. Employing SPF protection for a given domain will stop the forging of emails generated with the domain. In layman's terms: activating this attribute for a domain creates a specific record in the Domain Name System (DNS) containing the IP of the servers that are permitted to send email messages from mailboxes using the domain. The moment this record propagates worldwide, it will exist on all of the DNS servers that direct the Internet traffic. Any time some email message is sent, the initial DNS server it uses tests if it originates from an authorized server. If it does, it is forwarded to the destination address, but if it doesn't come from a server part of the SPF record for the particular domain, it is discarded. In this way nobody can mask an e-mail address then make it look as if you are distributing spam. This approach is also identified as email spoofing.
