mail.app shows the wrong date for emails

Question

I have a very long history of emails 30+ years. Some of my old emails are showed with the wrong date in mail.app.

Example:

These are the headers after anonymizing the data:

Received: from speedy.grolier.fr (speedy.grolier.fr [194.158.97.87]) by ns.calvacom.fr (8.7.3/8.6.9) with ESMTP id OAA21857 for <*@*>; Fri, 6 Sep 1996 14:02:35 +0200 (MET DST)
Received: from *.club-internet.fr (ppp-207-54.neuilly.club-internet.fr [194.117.207.54]) by speedy.grolier.fr (8.7.5/MGC-960516) with ESMTP id OAA16943 for <*@*>; Fri, 6 Sep 1996 14:00:14 +0200 (MET DST)
X-UIDL: 842012897.000
Message-Id: <*@speedy.grolier.fr>
From: "*" <*@*>
To: "*" <*@*>
Subject: Re: Faites-vous connaitre
Date: Fri, 6 Sep 1996 13:56:38 +0200
X-MSMail-Priority: Normal
X-Priority: 3
X-Mailer: Microsoft Internet Mail 4.70.1132
Content-Transfer-Encoding: 8bit
MIME-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"

below the body of the email.

So we can see that

1. Received: has Fri, 6 Sep 1996 14:02:35 +0200 (MET DST) and Fri, 6 Sep 1996 14:00:14 +0200 (MET DST)
2. Date: has Fri, 6 Sep 1996 13:56:38 +0200

The displayed date is

So I checked with mdls

mdls  ~/Library/Mail/path_to_email/857941.emlx | grep -i date
kMDItemFSContentChangeDate = 2020-10-02 02:10:10 +0000
kMDItemFSCreationDate      = 2015-10-13 04:27:22 +0000

no useful data about the email itself. Let's check with mdimport

mdimport -t -d3  ~/Library/Mail/path_to_email/857941.emlx | grep -i date
    "_kMDItemContentChangeDate" = "2020-10-02 02:10:10 +0000";
    "_kMDItemCreationDate" = "2015-10-13 04:27:22 +0000";
    "_kMDItemExpirationDate" = "<null>";
    "com_apple_mail_dateLastViewed" = "2020-10-02 02:10:10 +0000";
    "com_apple_mail_dateReceived" = "2005-07-16 15:58:43 +0000";
    kMDItemContentCreationDate = "1996-09-06 11:56:38 +0000";
    kMDItemContentModificationDate = "2020-10-02 02:10:10 +0000";
    kMDItemDateAdded = "2020-10-02 02:10:11 +0000";
    kMDItemLastUsedDate = "2020-10-02 02:10:10 +0000";
    kMDItemTextContent = " cut the body of email ";

So I can see that "com_apple_mail_dateReceived" = "2005-07-16 15:58:43 +0000"; is the date retained by mail.app to display the date in the UI.

Now I'm trying to understand how to change that.

Even after doing a mdimport -i ~/Library/Mail/path_to_email/857941.emlx, the date doesn't change in com_apple_mail_dateReceived.

I'm testing on this mail, but I have thousands of emails in the same state with the wrong com_apple_mail_dateReceived.

Update

Using Catalina, the emlx files do not help anymore because the mails are now in a private DB. The issue now is how to change the metadata contained in this DB when they are wrong.

Update 2

Ok I probably understood where the wrong date is coming from. In the emlx file:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>conversation-id</key>
    <integer>378100</integer>
    <key>date-last-viewed</key>
    <integer>1601614618</integer>
    <key>date-received</key>
    <integer>1121529523</integer>
    <key>flags</key>
    <integer>9160621057</integer>
    <key>remote-id</key>
    <string>21</string>
</dict>
</plist>

Then let's try to convert the Epoch date to a normal date.

% date -r 1121529523
Dim 17 jul 2005 00:58:43 JST

So now, we need to figure out if we change the date of the emlx file and try to reimport it, if it fixes the DB.

Answer 1

So… it almost looks like a bug from Mail.app

I tried to modify manually the file to have the right date in the plist and with the right content-size at the top. And the new import converted it back to the date of 2005. I sent a bug report to Apple about it.