[Exim] How to run a lot of domain rewrites with Exim

I want to rewrite a lot of domains with exim, what do I have to do

eg.

@thisone.nl        -->       @thisone.net
@this.nl        -->    @why.com
@what.nl    -->    @now.nl

It has to be a flexible sollution so I could change things "on the fly"
--
Mvg.,

Roger

-- Running Redhat 7