Sender Policy Framework, or SPF, is a verification system, that is intended to stop the so-called email spoofing where an e-mail message is sent from one email address, but to seem as being sent from another one, often with the purpose to scam the recipient in some way. If SPF protection is activated for a domain name, a unique record is created for it in the Domain Name System and all DNS servers around the world get it. The record contains all email servers that are permitted to send valid messages from an address under the domain. When a message is sent, the first DNS server it goes to verifies the SPF record and when the sending server is permitted, the message is sent to the targeted receiver. When, however, the sending server is not present in the SPF record for the specified domain, the e-mail message will not be sent and it will be discarded. Whenever you use this solution, it'll prevent third parties from sending spam emails that appear to have been sent by you.