By default, Thunderbird shows only the Date and sender’s name when you reply a mail.
The information is not enough when you would like to trace e-mail conversion later on.
Therefore, I introduce you to use this 3rd party plug-in called “Change quote and reply format” created by Kaosmos
The reply header after using the plug-in:
—- Original message —–
Subject: something
From: email@provider.com
To: email@provider.com
Date: 01/01/2005