Is it ok to remove Exchange Attributes from Administrator account - SBS2003

Hi,

As per the title?

I am licenced per mailbox for my AV and am 1 over - instead of buying another block of 5 licences - is it ok to remove the exchange attributes for the domain admin user account?

That box doesnt recieve mail - last recieved was May 2011. It has no use to recieve mail.

Exchnage NDR's go elsewhere.

Is it save thing to do to SBS2003?

Thanks