Sender Policy Framework, or SPF, is a validation system, that is designed to prevent the so-called email spoofing where an e-mail message is sent from one e-mail, but to seem as being sent from a different, often with the objective to fraud the recipient for some reason. When SPF protection is enabled for a domain, a specific record is generated for it in the Domain Name System and all of the DNS servers worldwide get it. The record includes all of the email servers that are permitted to send authentic messages from an email address under the domain. When a message is sent, the first DNS server it goes to checks the SPF record and if its sending server is permitted, the message is sent to the targeted receiver. When, however, the sending server doesn't exist in the SPF record for the particular domain, the message will not be forwarded and it will be removed. In the event that you employ this service, it will stop third parties from sending spam emails which look as if they have been sent by you.