[Firehol-support] DNS-based blacklisting

[Daniel L. Miller]

I'm probably messing with something I shouldn't be here - but is there a 
way to have rejections based on a dynamic real-time blacklist (DNS lookup)?

As an example - I may have a RBL I maintain for blocking e-mail 
spammers.  As I have no earthly reason to accept connections of any kind 
from these locations - I'm curious if I can block them at an IP level - 
before they ever reach my mail server.

Daniel