SPF, which means Sender Policy Framework, is an email safety system, which is used to validate if an email message was sent by an official server. Using SPF protection for a given domain will prevent the counterfeiting of email addresses made with the domain. In simple words: activating this feature for a domain creates a special record in the Domain Name System (DNS) which contains the IP of the servers that are allowed to send emails from mailboxes using the domain. As soon as this record propagates globally, it will exist on all the DNS servers that direct the Internet traffic. Every time an email message is sent, the initial DNS server it goes through checks whether it originates from an official server. If it does, it is forwarded to the destination address, but if it doesn't come from a server listed in the SPF record for the domain, it's discarded. In this way nobody will be able to mask an e-mail address and make it look as if you are e-mailing spam. This approach is also referred to as email spoofing.