SPF, which stands for Sender Policy Framework, is an e-mail security system, which is employed to confirm if an e-mail message was sent by a certified server. Employing SPF protection for a given domain will stop the counterfeiting of email addresses made with the domain. In layman's terms: activating this attribute for a domain name makes a specific record in the Domain Name System (DNS) containing the IP addresses of the servers that are allowed to send e-mails from mailboxes using the domain. Once this record propagates worldwide, it will exist on all the DNS servers that direct the Internet traffic. Whenever an email message is sent, the first DNS server it goes through verifies if it comes from an approved server. When it does, it is sent to the destination address, yet if it doesn't originate from a server indexed in the SPF record for the domain, it is discarded. Thus nobody will be able to mask an e-mail address then make it look as if you are distributing spam messages. This method is also termed email spoofing.
