Chill guys...
I think that you took each other way out of context.
Asia is cool, I don't think anyone is knocking that, I actually lived in Japan for awhile and had a great time...
now lets get back on track:
I would try adding some more RBL's (real time blocklists) first.
I recomend the spamcop blocklist and the spamhaus blocklists if you dont already have them, dynablock is pretty good from my experience too.
jesper has a whole list on his site to get the exact URL's
if you really want to block email from a whole ip range, maybe doing that at the firewall level would be better?
Have a good weekend,
-M