[exim] Deliver mail to a remote mailserver after virus- and …

I want to check virus and spam on my mailserver for a client, but
then deliver all the mail for their domain to their local mailserver.

Could someone give me a hint what to put in my configuration
file to make this happen?

I am using Exim 4.41, together with SpamAssassin, Amavis and
Clamav on Mac OS X 10.2.