SPF, which means Sender Policy Framework, is an e-mail safety system, which is used to confirm whether an email message is sent by an official server. Using SPF protection for a given domain name will stop the forging of email addresses made with the domain. In layman's terms: activating this function for a domain generates a particular record in the Domain Name System (DNS) which contains the IP addresses of the servers that are allowed to send e-mail messages from mailboxes under the domain. As soon as this record propagates worldwide, it exists on all of the DNS servers that direct the Internet traffic. When some e-mail message is sent, the first DNS server it goes through checks if it originates from an accredited server. If it does, it is forwarded to the destination address, but if it does not come from a server listed in the SPF record for the domain, it's discarded. Thus nobody can mask an email address and make it look as if you're distributing spam messages. This method is also called email spoofing.