Hook Wordpress Pingback action to perform some operation

I have been trying to hook pingback_post action to perform some functionality (send a custom email to wp admin) whenever a pingback/linkback has been added on my wp post.

I dont know why the documentation is not available anymore on WP official page here:

http://ift.tt/1NDVGBt

I am using following code in my functions.php file but its not working:

add_action('pingback_post','pingback_inserted',100,1);
function pingback_inserted($comment_id) {    
    wp_mail( get_option('admin_email'), 'Ping added', 'Ping added');        
}

Any help will be much appreciated. Thanks

via Chebli Mohamed