Sender Policy Framework, or SPF, is a validation system, that is intended to stop the so-called email spoofing where an e-mail message can be sent from one email address, but to seem as being sent from another, ordinarily with the objective to fraud the recipient for some reason. If SPF protection is enabled for a domain, a special record is made for it in the Domain Name System and all of the DNS servers worldwide get 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 first DNS server it encounters checks the SPF record and when its sending server is permitted, the message is sent to the targeted destination. When, however, the sending server is not included in the SPF record for the given domain, the e-mail message won't be sent and it'll be removed. If you employ this solution, it will stop third parties from sending spam messages which appear to have been sent by you.