Sender Policy Framework, or SPF, is a verification system, that is designed to prevent the so-called e-mail spoofing where an e-mail message is sent from one email address, but to look as being sent from a different, usually with the idea to fraud the recipient for some reason. If SPF protection is activated for a domain name, a unique record is generated for it in the Domain Name System and all of the DNS servers globally have it. The record includes all of the email servers that are allowed to send authentic messages from an address under the domain. When an e-mail is sent, the very first DNS server it encounters verifies the SPF record and if its sending server is permitted, the message is sent to the target receiver. When, however, the sending server is not included in the SPF record for the specified domain, the message won't be submitted and it will be discarded. In the event that you use this service, it will stop third parties from sending spam which look as if they have been sent by you.