Sender Policy Framework, or SPF, is a validation system, that is designed to prevent the so-called e-mail spoofing where an e-mail message can be sent from one email, but to appear as being sent from another one, usually with the objective to scam the recipient for some reason. When SPF protection is enabled for a domain, an exclusive record is made for it in the Domain Name System and all of the DNS servers globally have it. The record includes all email servers that are allowed to send legitimate messages from an email address within the domain. When an email is sent, the very first DNS server it encounters checks the SPF record and if the sending server is permitted, the message is forwarded to the target destination. In case, however, the sending server is not contained in the SPF record for the specified domain, the message will not be submitted and it will be discarded. Whenever you employ this service, it will prevent third parties from sending spam which look as if they have been sent by you.