Sender Policy Framework, or SPF, is a verification system, which is designed to stop the so-called e-mail spoofing where an email message is sent from one address, but to look as being sent from a different, usually with the objective to scam the recipient in some way. When SPF protection is enabled for a domain name, a unique record is generated for it in the Domain Name System and all DNS servers worldwide get it. The record contains all the email servers that are permitted to send authentic messages from an e-mail address part of 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 target receiver. If, however, the sending server is not included in the SPF record for the given domain, the e-mail message will not be sent and it will be removed. Whenever you use this service, it will stop third parties from sending spam messages which look as if they have been sent by you.