Is there a way to block http access if the source address traces back to a specific region or country in shorewall?

There was an article about that in a Magazine not too long ago. I couldn't find it on google however.

The gist of the article was reducing spam in your corporate mail server by blocking out blocks of IP address that are assigned to certain regions. The article mentioned which regions made good candidates.
There was one problem, because Korea (the source of a lot of abuse) is in the same block as Japan.

AfriNIC (African Network Information Centre) - Africa Region
APNIC (Asia Pacific Network Information Centre) - Asia/Pacific Region
ARIN (American Registry for Internet Numbers) - North America Region
LACNIC (Regional Latin-American and Caribbean IP Address Registry) – Latin America and some Caribbean Islands
RIPE NCC (Réseaux IP Européens) - Europe, the Middle East, and Central Asia

The list below shows the current IP v4 address space. However there are many identified as simply "various".
http://www.iana.org/assignments/ipv4-address-space

I've used hostip.info. They have an easy little api to return the probable location of the user. It really cut down my fraudulent orders. You can also download their d/b, but it's pretty large.

What can a person do who is on the other end of this dilemma. I am a US citizen and for many years used Comcast as my ISP. I was a very good customer. I relocated to Europe and Comcast has now considered my new ISP as a source of SPAM. I have never sent SPAM in my life and have never been informed that my address was ever used for that purpose. I now find that I cannot reach many of my friends due to this blocking. Comcast has no interest what so ever in trying to correct the problem. All they say, more or less, is tell your ISP to clean up their act. That doesn't work and appears to be them asking me to do their job.

My question is, what can a single individual, who did nothing wrong in the first place, do to get out from under one of these major blocking attacks?

What do you mean when you say that you cant reach your friends?
What method of contact are you trying to use?

I am trying to e-mail people with a xxx@comcast.net address. I get bounced as blacklisted. When I contact Comcast they tell me to get my ISP to clean up it's act. Every once in a while I seem to get through and then I restart my system and I'm blocked again. I'm guessing they might be checking my IP address and letting me through, but my ISP, as with most, is DHCP so I change IP address when I restart the system. At this moment I am again blocked as blacklisted. I've been trying for 3 months to get some reasonable response from them to let me e-mail with my Comcast friends.

I have a suggestion for you but I am not going to place it in this forum for spammers/scammers to read. If you would like to hear the suggestion then contact me on yahoo messenger. My yahoo id is vbsaltydog