setting up my own RBL server for postfix

I would like to setup my own rbl server for use with postfix.

1. Caching
2. The rbl server would reach out to a list of rbl servers.
3. I would also like to be able to collect stats to see if rbl servers are worth having on the list. If it had too many false neg/pos I would remove it. Think a rbl version of virustotal, but locally.

I found rbldnsd, but it hasn't been maintained since 2015, and it doesn't even respond on port 53 (also tried 55,1025,9999 for fun) which it binds to but does nothing with it. Also no helpful docs.

drwxr-xr-x 1 rbldns rbldns ? 110 Dec 29 22:00 .
drwxr-xr-x 1 rbldns rbldns ?   8 Dec 29 18:29 ..
-rw-rw-r-- 1 rbldns rbldns ?   0 Dec 29 18:43 127.0.0.1
-rw-rw-r-- 1 rbldns rbldns ?  31 Dec 29 19:01 forward
-rwxrwxrwx 1 rbldns rbldns ?   0 Dec 29 19:52 rbl.log
-rw-rw-r-- 1 rbldns rbldns ?  73 Dec 29 22:00 spammerlist
-rw-r--r-- 1 root   root   ?   0 Dec 29 18:29 spammerlist~
-rw-rw-r-- 1 rbldns rbldns ?   0 Dec 29 18:29 whitelist

ls -alZ /var/lib/rbldns/

drwxr-xr-x 1 rbldns rbldns ?   8 Dec 29 18:29 .
drwxr-xr-x 1 root   root   ? 560 Dec 29 18:29 ..
drwxr-xr-x 1 rbldns rbldns ? 110 Dec 29 22:00 dsbl

./rbldnsd -l rbl.log -f -r/var/lib/rbldns/dsbl/ -b 127.0.0.1 test:ip4set:spammerlist,whitelist bl.spamcom.net:generic:forward

I also tried "127.0.0.1:ip4set:spammerlist,whitelist", and dozens of other things.

netstat -an |grep 53

shows them just fine, but I can even connect with netcat -u. It does accept text but does nothing with it.

Server:         127.0.0.1
Address:        127.0.0.1#53

** server can't find www.whatever.com: REFUSED