[Exim] Auth + relay + multiple domain files

Using: exim 3.3x on Debian stable (Woody)

I am trying to get exim to auth. users on their from field, which is
used to lookup in a file to check if password and user name are
correct. But neither the exim docs or online searches have helped me
much.

How I perceive the setup (user domain do not resolve to the used IP,
but the server domain and IP matches):

user1@domain1 and user2@domain1 wil have their auth username and
password (server_condition) checked in
/etc/exim/virtual/domain1/password
user3@domain2 in /etc/exim/virtual/domain2/password

Is this possible at all?

...sorry about the bad english XD

--
Thomas Klietsch
m a t h n e s s @ z 4 2 . d k