Sender Policy Framework, or SPF, is a validation system, which is designed to prevent the so-called email spoofing where an email message can be sent from one e-mail address, but to look as being sent from another, ordinarily with the purpose to fraud the recipient someway. When SPF protection is enabled for a domain, a specific record is created for it in the Domain Name System and all DNS servers globally have it. The record features all of the email servers that are allowed to send authentic messages from an address part of the domain. When an e-mail is sent, the first DNS server it goes to checks the SPF record and in case the sending server is permitted, the message is forwarded to the targeted destination. In case, however, the sending server is not included in the SPF record for the given domain, the message won't be submitted and it'll be removed. When you use this service, it'll stop third parties from sending spam e-mails that appear to have been sent by you.