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 address, but to look as being sent from another, typically with the idea to scam the recipient someway. If SPF protection is activated for a domain, an exclusive record is generated for it in the Domain Name System and all DNS servers worldwide receive it. The record features all of the email servers that are permitted to send authentic messages from an e-mail address part of the domain. When an e-mail is sent, the first DNS server it goes to checks the SPF record and when the sending server is permitted, the message is sent to the targeted destination. When, however, the sending server doesn't exist in the SPF record for the specified domain, the message won't be sent and it will be removed. In case you employ this solution, it'll prevent third parties from sending spam messages that appear to have been sent from you.