[Exim] Deliver mail to a specify host

sorry for my english

I have a domain nussbaum.ch. The delivery is local to a pop3 server. Now
I need to configure some people to deliver the mail over an second smtp
server.

Our MX-Host is mail.nussbaum.ch. The most People get the mail via this
host. But a small group of people want use an exchange server :-(. Now I
don't know how I can put the mail of this group to the exchange server.

A sample address should be exchangeuser@???.

Thanks for help

Regards Markus