Sender Policy Framework, or SPF, is a validation system, which is intended to prevent the so-called e-mail spoofing where an email message can be sent from one email address, but to look as being sent from a different one, often with the objective to fraud the recipient in some way. When SPF protection is activated for a domain name, a unique record is made for it in the Domain Name System and all the DNS servers worldwide have it. The record contains all of the e-mail servers that are allowed to send authentic messages from an email address part of the domain. When an email is sent, the first DNS server it encounters verifies the SPF record and in case the sending server is authorized, the message is forwarded to the target destination. When, however, the sending server is not included in the SPF record for the given domain, the email message will not be sent and it will be removed. In the event that you employ this solution, it will stop third parties from sending spam e-mails that seem to have been sent by you.