Sender Policy Framework, or SPF, is a verification system, that is used to stop the so-called email spoofing where an e-mail message is sent from one email, but to look as being sent from another, usually with the objective to scam the recipient someway. When SPF protection is enabled for a domain name, a specific record is created for it in the Domain Name System and all DNS servers globally get it. The record includes all of the email servers that are permitted to send legitimate messages from an address under the domain. When an e-mail is sent, the very first DNS server it encounters verifies the SPF record and if its sending server is permitted, the message is forwarded to the targeted receiver. In case, however, the sending server doesn't exist in the SPF record for the given domain, the email message will not be sent and it'll be removed. When you employ this service, it'll prevent third parties from sending spam that seem to have been sent from you.