Sender Policy Framework, or SPF, is a validation system, which is employed to stop the so-called email spoofing where an email message is sent from one e-mail, but to seem as being sent from a different, usually with the idea to fraud the recipient in some way. If SPF protection is activated for a domain name, an exclusive record is generated for it in the Domain Name System and all of the DNS servers globally receive it. The record includes all of the email servers that are permitted to send authentic messages from an address under the domain. When an e-mail is sent, the first DNS server it goes to verifies the SPF record and when its sending server is permitted, the message is sent to the target receiver. If, however, the sending server is not contained in the SPF record for the given domain, the message won't be forwarded and it'll be removed. In the event that you use this service, it will prevent third parties from sending spam messages which look as if they have been sent from you.