Sender Policy Framework, or SPF, is a validation system, which is designed to stop the so-called email spoofing where an email message is sent from one address, but to look as being sent from a different one, frequently with the idea to fraud the recipient someway. If SPF protection is enabled for a domain name, a specific record is generated for it in the Domain Name System and all DNS servers globally have it. The record features all of the e-mail servers that are allowed to send legitimate messages from an email address under the domain. When an email is sent, the very first DNS server it encounters checks the SPF record and if its sending server is permitted, the message is forwarded to the target destination. When, however, the sending server is not included in the SPF record for the given domain, the email message won't be sent and it'll be discarded. If you employ this solution, it'll stop third parties from sending spam e-mails which seem to have been sent from you.