Sender Policy Framework, or SPF, is a verification system, that is intended to prevent the so-called e-mail spoofing where an email message is sent from one e-mail, but to look as being sent from another one, often with the idea to fraud the recipient for some reason. When SPF protection is activated for a domain, a special record is made for it in the Domain Name System and all DNS servers globally get it. The record contains all the mail servers that are permitted to send authentic messages from an email address within the domain. When a message is sent, the very first DNS server it encounters verifies the SPF record and when the sending server is authorized, the message is sent to the targeted destination. If, however, the sending server doesn't exist in the SPF record for the given domain, the e-mail message will not be forwarded and it will be removed. In the event that you employ this solution, it'll prevent third parties from sending spam e-mails that appear to have been sent by you.