Sender Policy Framework, or SPF, is a validation system, which is intended to prevent the so-called email spoofing where an e-mail message is sent from one e-mail address, but to look as being sent from a different, frequently with the objective to scam the recipient for some reason. When SPF protection is enabled for a domain, a special 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 legitimate messages from an address within the domain. When an email is sent, the very first DNS server it goes to verifies the SPF record and when its sending server is permitted, the message is sent to the targeted destination. When, however, the sending server is not contained in the SPF record for the particular domain, the e-mail message won't be sent and it will be discarded. When you use this service, it'll prevent third parties from sending spam messages which look as if they have been sent by you.