Sender Policy Framework, or SPF, is a verification system, which is intended to prevent the so-called email spoofing where an email message is sent from one e-mail, but to appear as being sent from another, usually with the idea to fraud the recipient for some reason. When SPF protection is enabled for a domain, a special record is created for it in the Domain Name System and all of the DNS servers worldwide get it. The record contains all the mail servers that are allowed to send legitimate messages from an address part of the domain. When an e-mail is sent, the first DNS server it goes to checks the SPF record and if the sending server is authorized, the message is forwarded to the targeted destination. If, however, the sending server is not present in the SPF record for the specified domain, the e-mail message won't be sent and it'll be discarded. When you employ this service, it will prevent third parties from sending spam emails which look as if they have been sent by you.