[exim] Anyway to catch error and defer/retry in system_filte…

I'm using the system_filter to automatically archive emails to another
server. It had been working fine for a while. But now due to some
unknown and intermittent DNS issue, I'm getting the unrouteable
address error a few times an hour.

The problem here is that exim does not attempt to defer and retry but
fail immediately with an error to both sender and the admin email.

Is there a way to catch such error and/or make exim defer to retry
while I try to resolve the DNS problem?

The code that I'm using for this is

if $sender_address_domain is mydomain.com
then
unseen deliver ${sender_address_local_part}_out@??? errors_to
hostmaster@???
endif