send-email: show the new message id assigned by outlook in the logs

send-email: show the new message id assigned by outlook in the logs

Whenever an email is sent, send-email shows a log at last, which
contains all the headers of the email that were received by the
receipients.

In case outlook changes the Message-ID, a log for the same is shown to
the user, but that change is not reflected when the log containing all
the headers is displayed. Here is an example of the log that is shown
when outlook changes the Message-ID:

Outlook reassigned Message-ID to: <PN3PR01MB95973E5ACD7CCFADCB4E298CB865A@PN3PR01MB9597.INDPRD01.PROD.OUTLOOK.COM>
OK. Log says:
Server: smtp.office365.com
MAIL FROM:<gargaditya08@live.com>
RCPT TO:<negahe7142@nomrista.com>
From: Aditya Garg <gargaditya08@live.com>
To: negahe7142@nomrista.com
Subject: [PATCH] send-email: show the new message id assigned by outlook in the logs
Date: Mon, 26 May 2025 20:28:36 +0530
Message-ID: <20250526145836.4825-1-gargaditya08@live.com>
X-Mailer: git-send-email @GIT_VERSION@
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

Result: 250

Fix this by updating the $header variable, which has the message ID we
internally assigned on the "Message-ID:" header, with the message ID the
Outlook server assigned. It should look like this after this patch:

OK. Log says:
Server: smtp.office365.com
MAIL FROM:<gargaditya08@live.com>
RCPT TO:<negahe7142@nomrista.com>
From: Aditya Garg <gargaditya08@live.com>
To: negahe7142@nomrista.com
Subject: [PATCH] send-email: show the new message id assigned by outlook in the logs
Date: Mon, 26 May 2025 20:29:22 +0530
Message-ID: <PN3PR01MB95977486061BD2542BD09B67B865A@PN3PR01MB9597.INDPRD01.PROD.OUTLOOK.COM>
X-Mailer: git-send-email @GIT_VERSION@
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

Result: 250

Signed-off-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>