Sender Policy Framework, or SPF, is a validation system, that is employed to prevent the so-called email spoofing where an e-mail message is sent from one address, but to look as being sent from a different one, often with the purpose to fraud the recipient for some reason. If SPF protection is activated for a domain, a unique record is created for it in the Domain Name System and all the DNS servers globally receive it. The record includes all the mail servers that are permitted to send valid messages from an email address within the domain. When an e-mail is sent, the first DNS server it goes to checks the SPF record and if the sending server is authorized, the message is forwarded to the targeted destination. If, however, the sending server is not included in the SPF record for the particular domain, the e-mail message will not be sent and it will be discarded. When you use this solution, it'll prevent third parties from sending spam messages that seem to have been sent from you.