Sender Policy Framework, or SPF, is a verification system, that is used to prevent the so-called e-mail spoofing where an email message is sent from one e-mail address, but to seem as being sent from another one, typically with the purpose to fraud the recipient in some way. When SPF protection is activated for a domain name, a unique record is created for it in the Domain Name System and all the DNS servers worldwide receive it. The record includes all of the email servers that are allowed to send valid messages from an address within the domain. When an e-mail is sent, the very first DNS server it goes to verifies the SPF record and if the sending server is permitted, the message is forwarded to the targeted receiver. In case, however, the sending server is not included in the SPF record for the specified domain, the e-mail message will not be submitted and it'll be discarded. When you employ this solution, it will prevent third parties from sending spam emails which look as if they have been sent by you.