How to add Date: header to received emails without break DKIM signatures

Some server send email without Date header, and Thunderbird doesn't recognize the date.So, I want to use following settings and add Date header. local_header_rewrite_clients = permit_inet_interfaces, ermit_sasl_authenticated always_add_missing_headers = yes But postfix.org says this may break DKIM signatures. Is there a way to add Date headers withoud break DKIM signatures ? (My mail server using DKIM.) Example of no Date header mail : Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on example.net X-Spam-Level: *** X-Spam-Status: No, score=3.7 required=8.0 tests=CONTENT_TYPE_PRESENT, FROM_MISSP_EH_MATCH,IP_LINK_PLUS,ISO2022JP_BODY,ISO2022JP_CHARSET, MISSING_DATE,MISSING_MID,NORMAL_HTTP_TO_IP,ONEGAI,QENCPTR1,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,RENRAKU,SPF_HELO_PASS,SPF_SOFTFAIL,TO_NO_BRKTS_FROM_MSSP autolearn=no autolearn_force=no version=3.4.0 X-Original-To: xxxxx@example.net Delivered-To: xxxxx@example.net Received: from xxxxx.example.org (xxxxx.example.org [xxx.xxx.xxx.xxx]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by example.net (Postfix) with ESMTPS id D53991D45 for ; Wed, 5 Sep 2018 20:44:48 +0900 (JST) DKIM-Filter: OpenDKIM Filter v2.11.0 example.net D53991D45 Received: from xxxxx.example.org (xxxxx.example.org [xxx.xxx.xxx.xxx]) by xxxxx.example.org (Postfix) with ESMTP id 77EFF8DC01 for ; Wed, 5 Sep 2018 20:44:48 +0900 (JST) Received: (qmail 23991 invoked by uid 101); 5 Sep 2018 20:44:43 +0900 Received: from unknown (HELO xxxxx.example.org) (xxx.xxx.xxx.xxx) by 0 with SMTP; 5 Sep 2018 20:44:43 +0900 Subject: ---email subject--- From: ---email subject--- To: ---email subject--- MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit X-Mailer: Bap Version1 ---email body---