[exim] Simple domain alias question

Hi

I'd like to set up an alias for

mail@???

to go to

mail@???

I understand there's a few different ways I can approach this. However,
first of all I am not sure if I need to include oracletc.co.uk in the
local domains, as part of the list of domains to relay for or neither. I
don't really want to relay because the machine at the receiving end will
be expecting the address to be a nedco.co.uk domain.

We're using the domain_aliases router from the exim4 FAQ already to
alias FQ domain names to local users.

I tried adding the following line:

mail@???: mail@???

A quick test with -bt however, indicates that the domain_aliases router
is not being used in the lookup.

I guess my first question has to be - can I do this with an alias,
without using address rewriting?

Thanks

Chris