[Exim] redirect question

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Hi there,

I am in the process of upgading from exim 3.x to 4. In previous version we used a director like this :

redirect_blah:
driver = smartuser
local_parts = ${local_part}
domains = one.domain.com
new_address = ${local_part}@???
no_verify

can anyone please point me in the right direction of give me an example router to be used in then new exim 4.20 configuartion.
Any help appreciated.

Regards
Nathan
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