Sender Policy Framework, or SPF, is a verification system, which is designed to prevent the so-called e-mail spoofing where an email message can be sent from one e-mail address, but to look as being sent from another one, generally with the purpose to fraud the recipient someway. If SPF protection is activated for a domain name, a special record is created for it in the Domain Name System and all DNS servers globally have it. The record features all the e-mail servers that are permitted to send authentic messages from an e-mail address part of the domain. When an email is sent, the very first DNS server it goes to verifies the SPF record and when the sending server is authorized, the message is forwarded to the target receiver. When, however, the sending server is not contained in the SPF record for the given domain, the email message will not be submitted and it will be removed. Whenever you employ this service, it'll stop third parties from sending spam e-mails that appear to have been sent by you.