Sender Policy Framework, or SPF, is a validation system, that is designed to stop the so-called e-mail spoofing where an e-mail message is sent from one email, but to seem as being sent from another, frequently with the purpose to scam the recipient for some reason. When SPF protection is enabled for a domain name, a unique record is made for it in the Domain Name System and all of the DNS servers around the world receive it. The record features all of the e-mail servers that are permitted to send valid messages from an address under the domain. When an email is sent, the very first DNS server it encounters verifies the SPF record and in case the sending server is permitted, the message is forwarded to the targeted destination. When, however, the sending server is not included in the SPF record for the particular domain, the email message won't be submitted and it'll be removed. In case you employ this service, it will prevent third parties from sending spam e-mails that look as if they have been sent from you.