sender policy framework (SPF)

The Sender Policy Framework(SPF) is a security procedure to distinguish spams from legal messages.

The SPF method works with reverse records that tell other mail servers that the outbound servers are allowed to send mails to their own server. The records are elaborated DNS TXT records that can be marked by a trust level. This allows the recipient's email system to evaluate the authenticity of the source. The SPF frameworkchecks whether the sender and its Simple Mail Transfer Protocol( SMTP) address are allowed to send messages via the mail server in question.