[exim] Life after code 550.

Usually I'm trying to send my mail directly. Sometimes remote host
doesn't want to accept it because my IP is dynamic and gives me code
550. After that I have a permanent failure, so I'm taking that
destination domain and inserting it into my smart route list, which
sends such mail to my provider's relay. I don't want to send all my
mail through provider. Period. I want to use that relay only in case
when direct delivery doesn't work for some reason. So we have a
fallback_hosts list made for this purpose, but problem is that code
5xx considered as fatal and exim doesn't try to use that fallback. So
the question - is there way to reroute mail in case of codes 5xx?