Sender Policy Framework, or SPF, is a verification system, that is used to stop the so-called e-mail spoofing where an e-mail message is sent from one email, but to seem as being sent from a different one, usually with the objective to scam the recipient in some way. If SPF protection is activated for a domain, a special record is generated for it in the Domain Name System and all of the DNS servers around the world get it. The record features all the email servers that are permitted to send authentic messages from an e-mail address within the domain. When an e-mail is sent, the first DNS server it encounters verifies the SPF record and if the sending server is authorized, the message is sent to the targeted receiver. When, however, the sending server is not included in the SPF record for the given domain, the email message will not be forwarded and it'll be removed. Whenever you employ this solution, it'll prevent third parties from sending spam emails that seem to have been sent by you.