Sender Policy Framework, or SPF, is a validation system, that is employed to prevent the so-called e-mail spoofing where an email message can be sent from one e-mail, but to appear as being sent from another one, generally with the objective to fraud the recipient for some reason. When SPF protection is activated for a domain name, an exclusive record is generated for it in the Domain Name System and all of the DNS servers around the world get it. The record features all of the e-mail servers that are permitted to send authentic messages from an address under the domain. When an email is sent, the first DNS server it goes to checks the SPF record and in case the sending server is authorized, the message is forwarded to the target destination. In case, however, the sending server is not contained in the SPF record for the particular domain, the message will not be sent and it will be discarded. Whenever you employ this solution, it'll stop third parties from sending spam messages that appear to have been sent by you.