Limit users to only send to a few recipients and more.......

Hi

I was asked if I can make a sollution like this :-)

1. Users are not allowed to see eachother in the addressbook

2. Users are not allowed to mail to eachother 

3. Users are ONLY allowed to mail to a few persons - and they are all outside this Exchange organisation.

Any good suggestions? :-)

It's a very special sollution, and very special customer :-)

BR
Steen