SPF, which stands for Sender Policy Framework, is an email safety system, which is used to confirm whether an e-mail message is sent by an official server. Using SPF protection for a domain will stop the counterfeiting of emails created with the domain. In simple words: activating this feature for a domain generates a particular record in the Domain Name System (DNS) which includes the IP addresses of the servers which are allowed to send e-mails from mail boxes using the domain. Once this record propagates worldwide, it will exist on all DNS servers that route the Internet traffic. Any time an email message is sent, the initial DNS server it uses tests if it originates from an approved server. In the event it does, it's forwarded to the destination address, yet when it does not come from a server part of the SPF record for the particular domain, it's 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 method is also called email spoofing.