[exim] Frustrating Routing Problem with Bad DNS

Here's the situation. I'm doing processing and forwarding. However
sometimes the host names I'm forwarding to have DNS problems. When this
occurs I want to forward the message to my "retry" server and get the
message out of the queue of the main server. So I tried the following
code - and it doesn't work.

process_and_forward_smtp:
driver = manualroute
domains = +preprocess_domains
condition = ${if match{$h_X-Spam-Class:}{SPAM-HIGH}{no}{yes}}
transport = process_and_forward_smtp
route_list = *
${lookup{$domain}dbm{/etc/exim/control/run/preprocess.db}{$value}{}}
.ifdef FALLBACKHOST
no_more
.else
fallback_hosts = retry.ctyme.com
.endif

.ifndef FALLBACKHOST
process_and_forward_smtp_bad_dns:
driver = manualroute
domains = +preprocess_domains
condition = ${if match{$h_X-Spam-Class:}{SPAM-HIGH}{no}{yes}}
transport = process_and_forward_smtp
route_list = * retry.ctyme.com
no_more
.endif

The idea being that if the first router failed because the host name
failed then it would fall through to the next router and forward to my
retry server. But I'm still just getting the DNS error.

How can I get this to work? What am I missing?

Thanks in advance.