[exim] Local users delivery problem

I'm running exim 4.44 and am working on a mail routing problem.

I want local users (specifically reports generated by my system) able to
generate mail to any local unqualified address (such as to "root" or any
other account) without making unqualified addresses world routable. No
matter what I come up with, EXIM unfailingly qualifies my unqualified
addresses and routes them.


I have two alias files: unqualified_aliases (root: user1, user2: user3,
user4: user@???) and qualified_aliases (user1@???: user1,
user2@???: user3, user4@???: user4).

How can I allow internal messages to address local addresses (like
root), but external messages from addressing them?

Clear as mud? Any help is appreciated.