WordPress: Modify WP registration signup email message and subject

functions.php

add_filter( 'wpmu_signup_user_notification_subject', 'we_modify_register_user_notification_subject', 10, 4 );
/**
 * Modify the user registration email activation subject
 */
function we_modify_register_user_notification_subject( $text ) {
	return 'Welcome to the Best Books on Writing site! (Activation Required)';
}

add_filter('wpmu_signup_user_notification_email', 'we_modify_register_user_notification_message', 10, 4);
/**
 * Modify the user registration email activation message
 */
function we_modify_register_user_notification_message($message, $user, $user_email, $key) {
	$message = sprintf(__(( "To activate your new account, please click the following link:\n\n%s\n\n After you activate, you will receive *another email* with your login information.\n\n" ),
			$user, $user_email, $key, $meta),site_url( "?page=gf_activation&key=$key" ));

		return sprintf($message);
}