add_filter ('preprocess_comment', 'check_comment_trolls');

function check_comment_trolls($data) {
// based on the code from the WordPress plugin impostercide
// http://wordpress.org/extend/plugins/impostercide/
// authors Mika Epstein and Scott Merrill

extract ($data);

if ('' != $comment_type) {
	// it's a pingback or trackback, let it through
	return $data;
}

get_currentuserinfo();

if ( is_user_logged_in() ) {
	// It's a logged in user, so it's good.
	return $data;
}

// array of valid users and their email username => email
$valid_users = array(
  'keesiemeijer' => 'keesiemeijer@email.com',
  'gariusthebrit' => 'gariusthebrit@email.com'
);

if(array_key_exists( $comment_author, $valid_users)) {
	if($comment_author_email != $valid_users[$comment_author]){
		// add comment to moderation queue
		add_filter('pre_comment_approved', '__return_zero');
	}
}
return $data;
}