Sender Policy Framework, or SPF, is a verification system, that is used to stop the so-called e-mail spoofing where an email message can be sent from one email, but to seem as being sent from a different one, often with the idea to fraud the recipient for some reason. If SPF protection is activated for a domain, an exclusive record is created for it in the Domain Name System and all DNS servers worldwide have it. The record includes all of the email servers that are allowed to send authentic messages from an e-mail address under the domain. When an email is sent, the very first DNS server it goes to verifies the SPF record and when its sending server is authorized, the message is sent to the targeted destination. In case, however, the sending server is not present in the SPF record for the given domain, the e-mail message will not be forwarded and it'll be discarded. When you use this solution, it will prevent third parties from sending spam e-mails which look as if they have been sent by you.