SPF, which is an acronym for Sender Policy Framework, is an e-mail safety system, that is used to confirm whether an e-mail message was sent by a certified server. Using SPF protection for a given domain will prevent the forging of email addresses generated with the domain. In simple words: enabling this attribute for a domain makes a special record in the Domain Name System (DNS) which includes the IP addresses of the servers which are permitted to send emails from mailboxes using the domain. As soon as this record propagates worldwide, it exists on all the DNS servers that direct the Internet traffic. Whenever a new e-mail message is sent, the initial DNS server it uses verifies whether it originates from an accredited server. If it does, it is forwarded to the destination address, however when it doesn't come from a server indexed in the SPF record for the domain, it is discarded. Thus nobody can mask an e-mail address then make it appear as if you're distributing spam messages. This technique is also identified as email spoofing.