Sender Policy Framework, or SPF, is a verification system, that is designed to stop the so-called e-mail spoofing where an email message is sent from one email, but to appear as being sent from a different one, generally with the purpose to fraud the recipient someway. When SPF protection is enabled for a domain, an exclusive record is generated for it in the Domain Name System and all the DNS servers worldwide get it. The record includes all of the e-mail servers that are permitted to send legitimate messages from an email address within the domain. When an email is sent, the first DNS server it encounters verifies the SPF record and when its sending server is permitted, the message is sent to the targeted receiver. If, however, the sending server is not present in the SPF record for the particular domain, the e-mail message will not be submitted and it will be removed. Whenever you use this solution, it'll stop third parties from sending spam messages that look as if they have been sent from you.