Sender Policy Framework, or SPF, is a validation system, that is intended to stop the so-called e-mail spoofing where an e-mail message is sent from one email, but to seem as being sent from another, usually with the purpose to fraud the recipient in some way. If SPF protection is activated for a domain name, a specific record is created for it in the Domain Name System and all DNS servers globally receive it. The record contains all of the mail servers that are allowed to send authentic messages from an email address under the domain. When an email is sent, the first DNS server it encounters verifies the SPF record and in case its sending server is permitted, the message is sent to the target receiver. If, however, the sending server is not included in the SPF record for the given domain, the e-mail message will not be submitted and it will be removed. In the event that you use this solution, it'll stop third parties from sending spam emails which appear to have been sent from you.