SPF, which means Sender Policy Framework, is an e-mail protection system, which is used to validate whether an email message was sent by a certified server. Employing SPF protection for a given domain name will prevent the forging of email addresses created with the domain. In simple words: activating this function for a domain name makes a particular record in the Domain Name System (DNS) containing the IP addresses of the servers which are allowed to send emails from mail boxes using the domain. The moment this record propagates worldwide, it will exist on all DNS servers that direct the Internet traffic. Whenever an email message is sent, the initial DNS server it uses verifies if it originates from an approved server. When it does, it's sent to the destination address, but if it does not originate from a server listed in the SPF record for the particular domain, it is rejected. In this way nobody will be able to mask an e-mail address then make it look as if you're e-mailing spam messages. This method is also identified as email spoofing.