[exim] rewrite condition

Hi All.

I have task with address rewriting.

I have to rewrite address *@first.dom to address *@second.dom but only
in case if the message sent to third.dom.

I suppose that it has to de rule like this:

*@first.dom      "${if eq {$domain}{third.dom} \
                          {$local_part@???}fail}" Ff

But it doesn't work :-(

Where is my mistake?

--
typus vulgaris