[exim] mail only for unix user

hi List,

i try tell exim not to use only local users to deliver mail, but i
dont find how.
Things ive found is the acl:

  accept domains = +local_domains
         endpass
         message = unknown user
         verify = recipient

who tells, that this user doesnt exists.
But i still dont know where exim get the user infos.
OK I Know from the /etc/passwd
But isnt a way to say to use rather a db file ?


Later in the config ive found:
check_local_user

are there other options except check_local_user ?


thanx,
luke