Realtime Blocking Lists are actually a good idea for fighting spam. You register open relays or spammers and you can use them to block them well on mail servers. The downside: apparently such services are only run by sociopaths or alternatively complete technical idiots.

SORBS belongs to the latter category. Just enter the IP 62.153.201.130 (a server I administer). What problem does it throw out? High-port-FTP-server. So FTP servers on ports that deviate from the standard.

Great. What's unusual about that? Pretty much every Zope server has something like that (and the high-port FTP on 8021 is exactly that - a Zope). And the other two are simply private FTP servers for two users that happen to run on different ports because the main FTP server is on the same IP anyway...

Here you can find the original article.