[Exim] Exim and separate passwd file

Hi all,

I'm trying to convince exim to *only* use a separate password file
instead of pam. So far I haven't found anything in the exim book or the
internet covering that. Perhaps it's too obvious.... My /etc/exim/passwd
file seems to be well formatted since exim is able to relay if I
authenticate over this passwd file (checked that with different
passwords in /etc/shadow and /etc/exim/passwd). But for downloading
messages it still uses pam. Does anybody have a clue how to change this?
I'm running exim 3.35-1 on debian.

Andi