Sender Policy Framework, or SPF, is a validation system, which is designed to prevent the so-called email spoofing where an email message is sent from one email address, but to appear as being sent from a different one, typically with the idea to fraud the recipient someway. If SPF protection is enabled for a domain name, a special record is generated for it in the Domain Name System and all DNS servers worldwide have it. The record contains all email servers that are permitted to send authentic messages from an email address part of the domain. When an e-mail is sent, the first DNS server it goes to checks the SPF record and in case its sending server is authorized, the message is forwarded to the targeted receiver. In case, however, the sending server is not included in the SPF record for the given domain, the message will not be submitted and it will be removed. Whenever you employ this solution, it'll stop third parties from sending spam that appear to have been sent by you.