[Exim] qualify_recipient in smartuser?

I am trying to migrate a large mailserver from sendmail to exim and
everything is going good so far. One stumbling block I have encounters
is the following..

There is a db setup in the following format..

user@???                destination@???
user2@???              destination2@???

and some are setup like..

user@???        local_pop_box

The last example has no @domain.com, which exim does not like. For the time
being it's not workable for various reasons to rewrite the scripts that
write this file, so I was wondering if there was a way to do this with some
form of qualify_recipient in the smartuser driver.

Here is the director I am using..

driver = smartuser
domains = db;/etc/domainlist.db
new_address = ${lookup{$local_part@$domain}dbm{/etc/exim/domainaliases.db}{$value}{${lookup{$domain}dbm{/etc/exim/domainaliases.db}{$value}fail}}}

Any insight is appriciated.

Spencer.