Sender Policy Framework, or SPF, is a verification system, which is employed to stop the so-called e-mail spoofing where an email message can be sent from one address, but to seem as being sent from another one, frequently with the objective to scam the recipient someway. If SPF protection is enabled for a domain name, a unique record is made for it in the Domain Name System and all of the DNS servers globally have it. The record includes all the e-mail servers that are permitted to send valid messages from an email address part of the domain. When an email is sent, the first DNS server it encounters checks the SPF record and if its sending server is authorized, the message is sent to the targeted destination. In case, however, the sending server is not included in the SPF record for the specified domain, the email message will not be forwarded and it'll be discarded. In the event that you use this solution, it'll stop third parties from sending spam messages which seem to have been sent from you.