Error message upon comment submission

This plugin would be great if I could turn off comment emailing. And if a commenter didn’t get the following error message upon submitting a comment. The comment goes through, but my readers think the comment doesn’t post when they see this error. Thanks for looking into it.

Warning: Missing argument 3 for Notify_Users_EMail::send_notification_comment() in /home/xxx/public_html/wp-content/plugins/notify-users-e-mail/notify-users-e-mail.php on line 461

Warning: Cannot modify header information – headers already sent by (output started at /home/xxx/public_html/wp-content/plugins/notify-users-e-mail/notify-users-e-mail.php:461) in /home/webmaster/public_html/wp-includes/pluggable.php on line 1178

https://ww.wp.xz.cn/plugins/notify-users-e-mail/