Sender Policy Framework, or SPF, is a validation system, that is used to stop the so-called email spoofing where an e-mail message is sent from one email address, but to look as being sent from another one, frequently with the purpose to scam the recipient someway. If SPF protection is enabled for a domain name, a special record is made for it in the Domain Name System and all of the DNS servers worldwide receive it. The record features all of the e-mail servers that are allowed to send authentic messages from an e-mail address within the domain. When an email is sent, the very first DNS server it encounters checks the SPF record and if its sending server is authorized, the message is forwarded to the target receiver. In case, however, the sending server doesn't exist in the SPF record for the specified domain, the e-mail message will not be forwarded and it will be discarded. When you employ this service, it'll prevent third parties from sending spam messages that seem to have been sent from you.