[Exim] rewrite configuration entry

I strip away the machine name from all my email records like so:

*@@  $1@PRIMARY_DOMAIN    fst
....

is there a way to preserve machine name for 1 user only? (root)
or in other words to *not* perform the rewrite for root ?

--
Jim Pazarena  Box 550                 mailto:paz@qcislands.net
              Queen Charlotte  BC     http://www.qcislands.net/paz
              CANADA   V0T 1S0        phone:250 559 7777