SPF, which is an acronym for Sender Policy Framework, is an email security system, which is used to verify if an e-mail message is sent by an official server. Using SPF protection for a given domain will stop the faking of email addresses created with the domain. In layman's terms: activating this feature for a domain name makes a particular record in the Domain Name System (DNS) that contains the IP addresses of the servers that are allowed to send e-mail messages from mailboxes under the domain. When this record propagates globally, it exists on all of the DNS servers that route the Internet traffic. Every time some e-mail message is sent, the initial DNS server it goes through checks if it originates from an authorized server. If it does, it is forwarded to the destination address, but when it doesn't originate from a server indexed in the SPF record for the domain, it's discarded. In this way nobody can mask an e-mail address to make it look as if you're e-mailing spam messages. This technique is also identified as email spoofing.