Sender Policy Framework, or SPF, is a verification system, that is intended to prevent the so-called email spoofing where an email message can be sent from one e-mail address, but to look as being sent from another, ordinarily with the purpose to fraud the recipient someway. When SPF protection is enabled for a domain, a unique record is created for it in the Domain Name System and all DNS servers worldwide receive it. The record contains all of the e-mail servers that are allowed to send legitimate messages from an address part of the domain. When a message is sent, the first DNS server it encounters verifies the SPF record and in case the sending server is authorized, the message is forwarded to the targeted destination. When, however, the sending server is not present in the SPF record for the specified domain, the email message will not be submitted and it'll be discarded. When you employ this service, it'll stop third parties from sending spam messages that appear to have been sent by you.