Sender Policy Framework, or SPF, is a validation system, that is designed to stop the so-called email spoofing where an email message can be sent from one e-mail address, but to look as being sent from a different, ordinarily with the objective to scam the recipient someway. If SPF protection is enabled for a domain, a unique record is generated for it in the Domain Name System and all DNS servers around the world have it. The record contains all of the email servers that are permitted to send valid messages from an email address within the domain. When a message is sent, the very first DNS server it encounters checks the SPF record and when the sending server is authorized, the message is forwarded to the target receiver. If, however, the sending server is not present in the SPF record for the particular domain, the message will not be submitted and it'll be removed. When you use this service, it will prevent third parties from sending spam messages that look as if they have been sent by you.