[Exim] redirect router READ alias file as particular user

I am in process of testing a new Exim setup of redirector systems for a

domain. Ideally, I would like to have a set of alias files in user home
directories, maintained by the users. I also want the home directories
private to the user.
I see Exim has an option to write to a file as a particular user, but I need
Exim to be able to lsearch this file as a specified user in order to verify
those aliased addresses.
The permissions on the directory are similar to:
drwx------    2 madison  users        4096 Jun 21 15:15 madison
There is a file in that directory with these permissions:
-rw-r--r--    1 madison  users        1205 Jun 21 15:15 madison.txt

Changing the directory permissions is not the preferred fix. But, I have
tested this by setting those permissions like:
drwxr-x---    2 madison  users        4096 Jun 21 15:15 madison

Exim was still unable to search the file. Again, I would rather leave the more
secure permissions and have Exim read the file in some other manner.
Is this at all possible?
If not, does anyone have any other possible alternatives?

Thanks,
--
David Monk
david@???