Thank you people. I swear I was searching on the whole Internet around 1 hour. I will try tomorrow at work to fix it and let you know here if I have some more issues.
Till now I can tell you that in Outlook 2007, by default, they where no show
Workaround: dragged and dropped the mail to the tasks panel to create a task which replicates the mail. Still I got stubborn and I would like to fix as you suggest.
Cheers