Sender Policy Framework, or SPF, is a validation system, that is employed to stop the so-called e-mail spoofing where an e-mail message is sent from one address, but to look as being sent from another one, generally with the purpose to fraud the recipient in some way. If SPF protection is enabled for a domain, a specific record is made for it in the Domain Name System and all of the DNS servers globally receive it. The record includes all email servers that are permitted to send legitimate messages from an address part of the domain. When an e-mail is sent, the first DNS server it goes to verifies the SPF record and if its sending server is permitted, the message is sent to the targeted receiver. In case, however, the sending server doesn't exist in the SPF record for the particular domain, the email message won't be submitted and it will be discarded. Whenever you employ this service, it'll stop third parties from sending spam e-mails that look as if they have been sent by you.