Sender Policy Framework, or SPF, is a verification system, which is employed to stop the so-called e-mail spoofing where an email message can be sent from one address, but to look as being sent from another one, usually with the idea to scam the recipient in some way. If SPF protection is enabled for a domain, a unique record is generated for it in the Domain Name System and all DNS servers globally receive it. The record features all mail servers that are allowed to send authentic messages from an email address within the domain. When a message is sent, the first DNS server it goes to verifies the SPF record and if its sending server is permitted, the message is sent to the target receiver. In case, however, the sending server is not present in the SPF record for the particular domain, the e-mail message will not be submitted and it will be discarded. In case you use this solution, it'll prevent third parties from sending spam emails which appear to have been sent from you.