SPF, which is an acronym for Sender Policy Framework, is an email protection system, which is designed to verify if an e-mail message is sent by an official server. Using SPF protection for a domain will stop the faking of email addresses created with the domain. In simple words: enabling 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 globally, it will exist on all the DNS servers that route the Internet traffic. Whenever an e-mail message is sent, the initial DNS server it uses verifies if it comes from an official server. If it does, it's forwarded to the destination address, however if it doesn't come from a server listed in the SPF record for the domain, it is discarded. In this way nobody will be able to mask an e-mail address to make it look as if you're sending spam. This technique is also termed email spoofing.