msn file transfer block

["Tolga Cengiz" <squid@xxxxxxxxxxxxxxxxxx>]

Hello

I m using iptables and transparent squid, I want to allow user for msn but 
mean time I want to restrict sending and receiving files through.Is it 
possible to do this through iptables or there is another way ?
I have controlled the mime types but I couldnt find anything to do. msn 
version  is 7.0. I m waiting your suggestions.

thanks