Sender Policy Framework, or SPF, is a verification system, that is intended to stop the so-called email spoofing where an email message is sent from one e-mail, but to seem as being sent from another one, ordinarily with the objective to fraud the recipient for some reason. If SPF protection is enabled for a domain name, a specific record is generated for it in the Domain Name System and all of the DNS servers around the world get it. The record includes all the email servers that are permitted to send valid messages from an address under the domain. When an e-mail is sent, the very first DNS server it goes to checks the SPF record and in case the sending server is authorized, the message is sent to the target destination. In case, however, the sending server is not included in the SPF record for the specified domain, the e-mail message will not be sent and it'll be removed. Whenever you employ this service, it'll stop third parties from sending spam messages that look as if they have been sent from you.