SPF, which stands for Sender Policy Framework, is an email safety system, that is designed to verify whether an email message was sent by a licensed server. Employing SPF protection for a domain will prevent the faking of email addresses made with the domain. In layman's terms: enabling this feature for a domain creates a special record in the Domain Name System (DNS) that contains the IP of the servers which are permitted to send e-mail messages from mailboxes using the domain. The moment this record propagates globally, it will exist on all the DNS servers that direct the Internet traffic. When an email message is sent, the initial DNS server it goes through verifies if it originates from an accredited server. When it does, it is sent to the destination address, yet when it doesn't originate from a server indexed in the SPF record for the domain, it's discarded. Thus nobody can mask an email address then make it appear as if you are sending spam. This technique is also termed email spoofing.