SPF, which stands for Sender Policy Framework, is an email protection system, which is is intended to validate whether an email message was sent by an authorized server. Employing SPF protection for a particular domain name will stop the counterfeiting of emails made with the domain. In layman's terms: activating this attribute for a domain name creates a specific record in the Domain Name System (DNS) which includes the IP addresses of the servers that are permitted to send email messages from mail boxes under the domain. As soon as this record propagates worldwide, it will exist on all the DNS servers that route the Internet traffic. Every time an e-mail message is sent, the initial DNS server it uses verifies whether it originates from an accredited server. When it does, it's forwarded to the destination address, however if it doesn't come from a server indexed in the SPF record for the particular domain, it is discarded. In this way nobody will be able to mask an e-mail address to make it appear as if you are sending spam messages. This approach is also referred to as email spoofing.
