SPF, which means Sender Policy Framework, is an e-mail safety system, which is is intended to verify if an e-mail message is sent by a certified server. Employing SPF protection for a given domain will prevent the counterfeiting of email addresses generated with the domain. In simple words: enabling this function for a domain makes a specific record in the Domain Name System (DNS) which contains the IP addresses of the servers which are allowed to send emails from mailboxes under the domain. The moment this record propagates worldwide, it will exist on all the DNS servers that direct the Internet traffic. When a new email message is sent, the first DNS server it uses tests whether it originates from an approved server. If it does, it is forwarded to the destination address, but when it does not come from a server part of the SPF record for the particular domain, it's rejected. In this way nobody can mask an email address to make it look as if you're e-mailing spam. This technique is also identified as email spoofing.