Sender Policy Framework, or SPF, is a validation system, which is employed to stop the so-called e-mail spoofing where an email message can be sent from one e-mail, but to seem as being sent from another, often with the idea to scam the recipient for some reason. When SPF protection is enabled for a domain, a specific record is created for it in the Domain Name System and all the DNS servers globally get it. The record contains all the email servers that are allowed to send legitimate messages from an address under the domain. When a message is sent, the very first DNS server it encounters checks the SPF record and in case its sending server is permitted, the message is forwarded to the targeted receiver. If, however, the sending server doesn't exist in the SPF record for the specified domain, the e-mail message will not be forwarded and it'll be removed. In the event that you use this solution, it will stop third parties from sending spam e-mails that seem to have been sent by you.