Sender Policy Framework, or SPF, is a verification system, that is employed to stop the so-called e-mail spoofing where an e-mail message is sent from one address, but to seem as being sent from a different one, usually with the purpose to fraud the recipient for some reason. When SPF protection is enabled for a domain, an exclusive record is made for it in the Domain Name System and all the DNS servers worldwide get it. The record features all the e-mail servers that are permitted to send legitimate messages from an email address part of the domain. When an e-mail is sent, the first DNS server it goes to verifies the SPF record and if its sending server is permitted, the message is forwarded to the target receiver. When, however, the sending server is not contained in the SPF record for the specified domain, the message will not be submitted and it will be removed. If you use this service, it will prevent third parties from sending spam e-mails that appear to have been sent by you.