SPF, which is short for Sender Policy Framework, is an email protection system, that is employed to verify whether an e-mail message is sent by a certified server. Using SPF protection for a domain name will stop the counterfeiting of email addresses generated with the domain. In layman's terms: activating this feature for a domain generates a special record in the Domain Name System (DNS) which contains the IP of the servers that are allowed to send email messages from mailboxes under the domain. As soon as this record propagates worldwide, it will exist on all of the DNS servers that direct the Internet traffic. When a new email message is sent, the first DNS server it goes through verifies if it comes from an authorized server. If it does, it's forwarded to the destination address, however when it doesn't come from a server listed in the SPF record for the domain, it is discarded. Thus nobody can mask an e-mail address to make it look as if you're e-mailing spam. This technique is also identified as email spoofing.