SPF, which is an acronym for Sender Policy Framework, is an email safety system, that is employed to verify whether an email message was sent by an official server. Using SPF protection for a given domain will stop the faking of email addresses created with the domain. In layman's terms: enabling this feature for a domain name creates a specific record in the Domain Name System (DNS) that contains the IP of the servers which are permitted to send email messages from mailboxes under the domain. The moment this record propagates globally, it will exist on all DNS servers that direct the Internet traffic. When some email message is sent, the initial DNS server it goes through checks whether it originates from an authorized server. When it does, it's forwarded to the destination address, yet if it doesn't originate from a server part of the SPF record for the particular domain, it's discarded. Thus nobody will be able to mask an e-mail address then make it appear as if you are e-mailing spam. This approach is also known as email spoofing.