SPF, which stands for Sender Policy Framework, is an email safety system, which is is intended to confirm if an e-mail message is sent by an official server. Using SPF protection for a domain will stop the faking of email addresses generated with the domain. In simple words: activating this function for a domain name creates a particular record in the Domain Name System (DNS) that contains the IP addresses of the servers which are allowed to send e-mail messages from mailboxes under the domain. When this record propagates globally, it will exist on all of the DNS servers that route the Internet traffic. Every time a new e-mail message is sent, the initial DNS server it uses verifies whether it comes from an approved server. If it does, it's sent to the destination address, however when it doesn't originate from a server indexed in the SPF record for the particular domain, it is rejected. In this way nobody can mask an e-mail address to make it look as if you're e-mailing spam. This approach is also known as email spoofing.