Disable Windows Message 5.1 Contact Popup

Hi,
I setup LCS 2003 and I would like to know if there is anyway to disable the
contact popup that appear on the Windows Message when you add someone to
your contact. Before I had Exchange 2000 chat and when I add someone to my
contact the receipent never receive a popup to allow or block the request.
Is there any way to disable to all the user without have to go to each and
everyone pc?

Thanks

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