[Exim] domain across 2 servers

Hi Guys

I need to configure Exim to be able to parse a text fill with users
names in it.

If the user name is in the file then it must forward the mail to another
mail server else
if the name doesn't exist in the file then it must delivery the mail
locally.

Is this possible ? Had anyone pulled it off ?

If so any help would be appreciated :)

Kind regards
Craig