Sender Policy Framework, or SPF, is a verification system, which is employed to stop the so-called e-mail spoofing where an e-mail message is sent from one address, but to look as being sent from another one, usually with the objective to scam the recipient someway. When SPF protection is activated for a domain, a unique record is made for it in the Domain Name System and all DNS servers globally have it. The record features all the mail servers that are allowed to send legitimate messages from an e-mail address under the domain. When a message is sent, the first DNS server it goes to checks the SPF record and in case its sending server is authorized, the message is forwarded to the target receiver. When, however, the sending server is not contained in the SPF record for the particular domain, the email message won't be submitted and it will be discarded. When you employ this service, it will stop third parties from sending spam messages which look as if they have been sent from you.