SPF, which is an acronym for Sender Policy Framework, is an email protection system, which is used to verify whether an e-mail message was sent by a certified server. Using SPF protection for a given domain name will prevent the forging of email addresses generated with the domain. In simple words: activating this function for a domain makes a specific record in the Domain Name System (DNS) which contains the IP of the servers that are permitted to send email messages from mailboxes under the domain. As soon as this record propagates globally, it exists on all DNS servers that route the Internet traffic. Any time an email message is sent, the first DNS server it goes through verifies if it originates from an authorized server. In the event it does, it is sent to the destination address, yet if it does not come from a server indexed in the SPF record for the particular domain, it is rejected. Thus nobody can mask an e-mail address then make it look as if you're distributing spam. This approach is also identified as email spoofing.