Sender Policy Framework, or SPF, is a verification system, that is designed to prevent the so-called e-mail spoofing where an email message can be sent from one address, but to look as being sent from a different one, typically with the idea to fraud the recipient someway. If SPF protection is activated for a domain, an exclusive record is generated for it in the Domain Name System and all DNS servers worldwide get it. The record includes all email servers that are permitted to send valid 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 in case its sending server is permitted, the message is sent to the target receiver. In case, however, the sending server is not contained in the SPF record for the specified domain, the e-mail message won't be forwarded and it will be discarded. If you use this solution, it'll stop third parties from sending spam e-mails that seem to have been sent by you.
