Sender Policy Framework, or SPF, is a validation system, that is intended to prevent the so-called e-mail spoofing where an e-mail message can be sent from one email, but to seem as being sent from a different, usually with the idea to scam the recipient someway. When SPF protection is activated for a domain, a specific record is generated for it in the Domain Name System and all the DNS servers worldwide have it. The record contains all the mail servers that are permitted to send valid messages from an e-mail address under the domain. When a message is sent, the first DNS server it encounters verifies the SPF record and if its sending server is authorized, the message is forwarded to the targeted receiver. If, however, the sending server doesn't exist in the SPF record for the particular domain, the e-mail message won't be submitted and it will be discarded. Whenever you employ this solution, it will prevent third parties from sending spam emails which seem to have been sent by you.