I've never run a Tor exit node, only relays. There's very little information available about what's happening. I've tried to get my router's IP address off the blacklist without success; entries don't seem to age off, at least not in the space of months. (For a few days I had the Tor relay running behind NAT forwarding on the router's IP address; later I got another static IP address for the relay machine's own use but the damage had already been done; now my router's IP address is blacklisted and I can't undo it---every machine on my home network behind that NAT is affected by the blacklist.