Sender Policy Framework, or SPF, is a verification system, that is employed to stop the so-called email spoofing where an email message can be sent from one e-mail address, but to look as being sent from a different one, often with the idea to scam the recipient for some reason. If SPF protection is enabled for a domain name, a unique record is generated for it in the Domain Name System and all of the DNS servers globally have it. The record contains all the e-mail servers that are permitted to send authentic messages from an e-mail address under the domain. When a message is sent, the very first DNS server it encounters checks the SPF record and in case the sending server is authorized, the message is sent to the targeted destination. In case, however, the sending server is not present in the SPF record for the particular domain, the email message won't be submitted and it'll be discarded. Whenever you employ this service, it will stop third parties from sending spam which seem to have been sent by you.