Outlook – export emails from PST file in Outlook 2010 to Thunderbird

I will start by describing the problem..

I had an email account configured in Outlook 2010 connected to an Exchange server.
I backed up my emails locally into a PST file.
(now I no longer have access to the Exchange account)

Next I wanted to export these archived mails to be used inside
Thunderbird 10.x (place them in the Local Folders in TB). The PST file is around 500MB in size.

I tried different methods:

• My first attempt was to use the Import > Mail > Outlook feature directly from inside TB as suggested here.
• In another attempt, I "copied" my emails (drag-drop) to a third common IMAP email configured in both Outlook and Thunderbird (which is in fact a locally running mail server on the 127.0.0.1 interface), then I pulled them into my local folder once inside TB.
• I even tried to use Outlook Express as an intermediary step (Outlook -> Outlook Express -> Thunderbird).

All the above fails, as the emails are not preserved when exported.
I have encountered a number of problems, to name a few:

• if we have Content-Type: multipart/alternative; emails with both html/text formats, then only the html one is exported.
• different encodings are sometimes used than the original ones (base64, quoted-printable, etc..)
• the history of routes (Received: headers) is completely gone
• the addresses are sometimes lost and simply the display name is kept. ex:
  To: "First Last" <nick@server.com> gets transformed into: To: "First Last"
• sometimes the whole sender/receiver address is lost, and simply duplicated from the opposite field
• the date field timezone gets changed to the current machine's timezone (not a biggie)
• all sorts of other headers are added/removed/rewritten differently…

So my question is how can I export emails from my PST file into Thunderbird's EML/MBOX textual format, in a clean way the preserves all the original headers?

I understand that the specification of PST files is now publicly available (right?), so I'm hoping someone developed a decent tool for this task.. The way I see it, if we somehow had access to the raw emails in Outlook (like view-source in TB), it shouldn't be hard to simply write them to text files!!

BTW: In Outlook Express we could directly choose File > Save As and export in .eml format, but Outlook 2010 only have the (proprietary?) binary .msg format option (or am I missing something)…

Here's a sample to show how the emails get mangled — names and other stuff have been changed to protect the innocent 🙂

Original email in Outlook (open email in new window, go to File > Properties and inspect the 'Internet headers' text field, although sometimes its just blank!)

Received: from mail.server (192.168.2.1)
 by s2.server (192.168.5.1) with Microsoft SMTP Server id 14.0.702.0; 
 Thu, 3 Feb 2011 12:51:26 -0500
Received: from mail.server (mail.server [192.168.6.1])
 by mail.server (8.14.5.Beta0/8.14.5.Beta0) with ESMTP id p00000000000002;
 Thu, 3 Feb 2011 12:51:26 -0500
Received: from smtp.server (smtp.server [192.168.4.1])
 by mail.server (8.14.5.Beta0/8.14.5.Beta0) with ESMTP id p00000000000001
 for <list@server>; Thu, 3 Feb 2011 12:51:16 -0500
Received: from s3.server (s4.server [192.168.3.1])
 by smtp.server (8.14.4/8.14.4) with ESMTP id p0000000000000
 for <list@server>; Thu, 3 Feb 2011 12:51:16 -0500 (envelope-from sender@server)
Received: from s1.server ([ffff::0000:000:0000:0000])
 by s3.server ([ffff::1111:000:0000:0000%12]) with mapi; 
 Thu, 3 Feb 2011 12:51:15 -0500
From: sender@server
Subject: test
Thread-Topic: test
Thread-Index: A0000000011112222333344445555g==
Date: Thu, 3 Feb 2011 12:51:15 -0500
Message-ID: <99887766554433221100FFEEDDCCBBAA99887766@s1.server>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
To: undisclosed-recipients:;
Return-Path: list-request@server
X-MS-Exchange-Organization-AuthSource: s2.server
X-MS-Exchange-Organization-AuthAs: Anonymous
X-MS-Exchange-Organization-AVStamp-Mailbox: MSFTFF;1;0;0 0 0
X-MS-Exchange-Organization-SCL: -1

Imported email into Thunderbird (simply Ctrl+U to view source)

From: sender@server
Subject: test
Thread-Index: A9999888877776666555544443333g==
Date: Thu, 3 Feb 2011 12:51:15 -0500
Message-ID: <99887766554433221100FFEEDDCCBBAA99887766@s1.server>
acceptlanguage: en-US
Content-Language: en-us
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
To: sender@server
X-Mailer: Microsoft Outlook 14.0
x-ms-exchange-organization-authsource: s2.server
x-ms-exchange-organization-authas: Anonymous
X-OlkEid: 00112233445566778899AABBCCDDEEFF00112233