Sender Policy Framework, or SPF, is a validation system, which is intended to prevent the so-called email spoofing where an e-mail message is sent from one email, but to seem as being sent from a different one, usually with the purpose to fraud the recipient for some reason. If SPF protection is enabled for a domain, a specific record is generated for it in the Domain Name System and all of the DNS servers around the world get it. The record contains all e-mail servers that are permitted to send authentic messages from an address part of the domain. When an e-mail is sent, the first DNS server it encounters verifies the SPF record and in case its sending server is authorized, the message is forwarded to the targeted destination. In case, however, the sending server is not contained in the SPF record for the particular domain, the e-mail message will not be submitted and it'll be removed. In the event that you employ this solution, it'll stop third parties from sending spam that seem to have been sent from you.