SPF, which stands for Sender Policy Framework, is an e-mail safety system, that is employed to confirm if an email message was sent by a certified server. Employing SPF protection for a domain will stop the counterfeiting of email addresses made with the domain. In simple words: enabling this feature for a domain makes a special record in the Domain Name System (DNS) that contains the IP of the servers that are allowed to send emails from mailboxes using the domain. When this record propagates globally, it exists on all of the DNS servers that route the Internet traffic. When a new email message is sent, the first DNS server it goes through checks if it originates from an official server. In the event it does, it is forwarded to the destination address, however if it doesn't originate from a server part of the SPF record for the particular domain, it's rejected. Thus nobody will be able to mask an email address to make it look as if you're e-mailing spam messages. This approach is also referred to as email spoofing.