[Exim] Default Alias Expansion

I'm trying to setup my mail servers to accept mail for a certain
domain, and forward that mail onto another server with the same local
part. In terms of an alias file :-

    *:    $1@???

However, as far as I can see there isn't a way of doing this with alias 
files. Can anyone confirm whether this is possible or not ?
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mike.meredith@???                http://www.iso.port.ac.uk/~mike
Senior Informatics Officer (Postmaster, Hostmaster, and security)