Sender Policy Framework, or SPF, is a validation system, that is designed to stop the so-called e-mail spoofing where an email message can be sent from one e-mail address, but to appear as being sent from another one, often with the idea to scam the recipient someway. When SPF protection is enabled for a domain, an exclusive record is generated for it in the Domain Name System and all DNS servers worldwide get it. The record includes all the email servers that are allowed to send legitimate messages from an e-mail address under the domain. When an email is sent, the first DNS server it encounters checks the SPF record and when the sending server is permitted, the message is forwarded to the target destination. In case, however, the sending server doesn't exist in the SPF record for the specified domain, the e-mail message will not be forwarded and it will be removed. Whenever you employ this service, it will stop third parties from sending spam that seem to have been sent from you.