Sender Policy Framework, or SPF, is a verification system, which is intended to prevent the so-called email spoofing where an email message is sent from one address, but to look as being sent from a different, typically with the objective to fraud the recipient someway. If SPF protection is activated for a domain name, a specific record is generated for it in the Domain Name System and all the DNS servers globally have it. The record contains all email servers that are permitted to send valid messages from an address under the domain. When an email is sent, the very first DNS server it goes to checks the SPF record and when the sending server is authorized, the message is sent to the targeted receiver. If, however, the sending server is not present in the SPF record for the given domain, the e-mail message won't be submitted and it'll be discarded. Whenever you employ this service, it will prevent third parties from sending spam emails which look as if they have been sent from you.