title: GMail messages show wrong date after import
body: <p>I have created a <strong>Google Apps</strong> account and then important my old email messages from my own IMAP-based mail server. For that purpose I used imapsync.
  There is some mails which show up <strong>fine</strong> when viewed in <strong>Thunderbird</strong> -- interestingly enough as well on the old IMAP server <strong>as on GMail</strong>. They correctly have the date of original sending at <strong>2nd of December 2008</strong>. When viewing the full mail source ("original message") from GMail web interface, its <strong>headers</strong> read (XXX for anonymization in some places):</p>
  
  <pre><code>X-Account-Key: account6
  X-UIDL: 10f6988675937085b6eXXX
  X-Mozilla-Keys:                                                                                 
  Return-Path: &lt;XXX@t-online.de&gt;
  X-Flags: 0000
  Delivered-To: GMX delivery to XXX@gmx.de
  Received: (qmail invoked by alias); 02 Dec 2008 09:16:48 -0000
  Received: from mailout09.t-online.de (EHLO mailout09.t-online.de) [194.25.134.84]
    by mx0.gmx.net (mx086) with SMTP; 02 Dec 2008 10:16:48 +0100
  Received: from fwd02.aul.t-online.de 
  by mailout09.sul.t-online.de with smtp 
  id 1L7RN9-XXX; Tue, 02 Dec 2008 10:16:47 +0100
  Received: from localhost (Tti8HrZYYh01uPSGlzL36WA4trfZ2XXX@[172.20.101.250]) by fwd02.aul.t-online.de
  with esmtp id 1L7RMr-XXX; Tue, 2 Dec 2008 10:16:29 +0100
  MIME-Version: 1.0
  Received: from 77.185.232.243:1675 by cmpweb16.aul.t-online.de with HTTP/1.1
   (Kommunikationscenter V9-2-23 on API V3-3-19)
  Date: Tue, 02 Dec 2008 10:16:29 +0100
  Reply-To: "XXX@t-online.de" &lt;XXX@t-online.de&gt;
  To: XXX@gmx.de
  X-Priority: 3
  X-UMS: email
  X-Mailer: TOI Kommunikationscenter V9-2-23
  Subject: XXX
  From: "XXX@t-online.de" &lt;XXX@t-online.de&gt;
  Content-Type: multipart/mixed;
  boundary="=_71bfbbb1eca6e77241917c40d55c1078"
  Message-ID: &lt;1L7RMr-XXX@fwd02.aul.t-online.de&gt;
  X-ID: Tti8HrZYYh01uPSGlzL36WA4trfZ2Ib9MXXX@t-dialin.net
  X-TOI-MSGID: 6a3e3035-aa28-XXX
  X-GMX-Antivirus: 0 (no virus found)
  X-GMX-Antispam: 0 (Mail was not recognized as spam)
  X-GMX-UID: GcoGeJ9WIyd1gjzXXX
  </code></pre>
  
  <p>But in the overview lists in the web interface it shows as dated <strong>7th of October 2011</strong>. This date might be the date of a previeous import (to my own IMAP server).</p>
  
  <p>But I have no idea where Google takes that date from and how I can change this date to the date the message was really sent. Any ideas?</p>