Sender Policy Framework, or SPF, is a verification system, that is used to stop the so-called e-mail spoofing where an e-mail message can be sent from one e-mail address, but to seem as being sent from a different one, ordinarily with the idea to scam the recipient for some reason. If SPF protection is enabled for a domain name, a unique record is made for it in the Domain Name System and all of the DNS servers around the world receive it. The record features all of the e-mail servers that are allowed to send authentic messages from an email address within the domain. When a message is sent, the very first DNS server it encounters verifies the SPF record and in case the sending server is authorized, the message is sent to the target receiver. In case, however, the sending server is not contained in the SPF record for the particular domain, the message will not be sent and it'll be removed. In case you employ this service, it will prevent third parties from sending spam emails that seem to have been sent from you.