SPF, which is short for Sender Policy Framework, is an email security system, that is designed to validate if an e-mail message is sent by a certified server. Using SPF protection for a domain will stop the faking of emails created with the domain. In layman's terms: activating this attribute for a domain generates a particular record in the Domain Name System (DNS) containing the IP addresses of the servers that are allowed to send e-mail messages from mailboxes under the domain. Once this record propagates worldwide, it will exist on all of the DNS servers that direct the Internet traffic. Whenever some e-mail message is sent, the first DNS server it uses verifies whether it comes from an official server. In the event it does, it is sent to the destination address, however when it does not originate from a server indexed in the SPF record for the particular domain, it's discarded. In this way nobody can mask an email address to make it look as if you are sending spam messages. This approach is also referred to as email spoofing.