Improvement of Legitimate Mail Server Detection Method using Sender Authentication

Anti-spam measures include methods for determining unsolicited email from the email content and methods for using sender information. If it can be determined from the sender's IP address of sender information and the sender's domain name whether the email should be received, it is possible to reduce the processing of the spam filter by the email content that has a high processing load for the determination. This study uses sender authentication technology to identify the sender of forwarded email. We consider that the sender of this forwarded email is the legitimate email sender to receive, and propose to use these as an allow list. In this paper, we propose a method to further improve the method we proposed and reduce misjudgment of the allow list. We verified that this new method is effective by using the log information of the emails actually received.