[exim] Match if previous router matched

Hi,

I want for backup purpose write all mails going to my smarthost a second
time in a file. Is it possible to match a router if the previous router
matched?

smarthost:
domains = !+local_domains
unseen

backup:
condition = smarthost matched
no_more

I want to avoid duplicate evaluation of the conditions. Another idea is:

skip_smarthost:
domain = +local_domains
self = pass
pass_router = after_smarthost

smarthost:
unseen

backup:
no_more

after_smarthost:

Better ideas?

Bye, Jörg.
-- 
Life can only be understood backwards, but it must be lived forwards.
                                             (Soren Kierkegaard)