SPF, which is short for Sender Policy Framework, is an e-mail security system, that is employed to validate whether an e-mail message was sent by a licensed server. Employing SPF protection for a domain name will stop the faking of email addresses generated with the domain. In simple words: activating this function for a domain generates a particular record in the Domain Name System (DNS) containing the IP of the servers which are allowed to send emails from mailboxes under the domain. As soon as this record propagates globally, it exists on all of the DNS servers that route the Internet traffic. Whenever some e-mail message is sent, the initial DNS server it goes through verifies whether it originates from an approved server. In the event it does, it is sent to the destination address, however when it doesn't come from a server listed in the SPF record for the domain, it is discarded. Thus nobody can mask an email address then make it appear as if you're sending spam. This approach is also identified as email spoofing.