Sender Policy Framework, or SPF, is a verification system, that is employed to stop the so-called e-mail spoofing where an email message can be sent from one e-mail, but to seem as being sent from another one, typically with the idea to scam the recipient in some way. If SPF protection is enabled for a domain name, a special record is created for it in the Domain Name System and all the DNS servers worldwide receive it. The record contains all the email servers that are allowed to send authentic messages from an address within the domain. When a message is sent, the first DNS server it encounters checks the SPF record and if the sending server is permitted, the message is forwarded to the targeted receiver. When, however, the sending server is not contained in the SPF record for the specified domain, the e-mail message won't be forwarded and it'll be removed. If you employ this service, it will stop third parties from sending spam messages which look as if they have been sent from you.