Sender Policy Framework, or SPF, is a validation system, that is designed to stop the so-called email spoofing where an email message is sent from one e-mail, but to appear as being sent from another, frequently with the objective to scam the recipient someway. When SPF protection is activated for a domain, a special record is made for it in the Domain Name System and all the DNS servers around the world receive it. The record contains all 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 verifies the SPF record and when its sending server is permitted, the message is forwarded to the targeted destination. When, however, the sending server is not contained in the SPF record for the particular domain, the email message will not be sent and it'll be removed. When you employ this solution, it will stop third parties from sending spam that seem to have been sent by you.