Visibilty of replies

I like Thunderbird very much and use it since many years. There is only one little thing…:
if I get answers to one of my outgoing mails
the answer stays invisible
because it has been automatically put to my original mail but -
that mail unfortuantely is NOT highlighted by bold letters

  • so I have to look up my old mails one after the other
    in order to find that one and single answer…
    Could that be changed somehow?
    Thank you
    Michael.