SPAMCONTROL is a patch to qmail by Erwin Hoffmann and others that adds many missing features to qmail when run as an Internet facing MTA in todays online world.
I have been using the greylisting implementation for qmail from
http://shupp.org/ which is based on the implementation for exim from
I wanted to add IPv6 support and found no references on the web
regarding greylisting and IPv6 (at least no implementation
is 188.8.131.52, you should upgrade to IPv6