Sender Policy Framework, or SPF, is a validation system, which is designed to stop the so-called e-mail spoofing where an email message is sent from one email, but to seem as being sent from another, usually with the idea to fraud the recipient someway. If SPF protection is activated for a domain, an exclusive record is created for it in the Domain Name System and all of the DNS servers globally have it. The record features all the mail servers that are allowed to send authentic messages from an email address part of the domain. When a message is sent, the first DNS server it encounters checks the SPF record and when the sending server is permitted, the message is forwarded to the targeted receiver. When, however, the sending server is not present in the SPF record for the particular domain, the e-mail message won't be sent and it'll be discarded. In case you employ this solution, it'll stop third parties from sending spam messages which seem to have been sent from you.