@ssuess– I would create a metabox with all the fields you want:

-author email: gets pulled in automatically
-message

Then in your regular plugin file or themes functions.php try something like this:

function email_on_post_status($post_id)
{
	global $post, $typenow;

	
	$post_status = get_post_status($post_id);

	//verify post is not a revision
	if (!wp_is_post_revision($post_id) && !wp_is_post_autosave($post_id))
	{
          //use get_post_meta to get author email and message. Pass to wp_mail

	 wp_mail($params);
	}
}
add_action('save_post', 'email_on_post_status', 1, 2);
add_action('transition_post_status', 'email_on_post_status', 10, 3);