You need to check the option to save a copy when sending a PM. Otherwise the default is not to save a copy. I will investigate but don't think this default PM behaviour can be changed.

I have been tossing a coin so to speak for a considerable time as to whether I should offer a copy of the ban list publicly or not. I've decided I will. A copy is attached below. This is a combination Japanese and Taiwanese list. Introduction then shows a list of the addresses arranged on separate lines. A 2nd list in middle of the document is the complete list, just in case you wanted to use more than I provided in the shorter list and use ranges of /19 or higher for the smaller sub-ranges. A 3rd list is provided at bottom of document describing how to add them to LimeWire. This 3rd list lists them horizontally exactly how LimeWire lists them. I hope that does not sound confusing.

The full list has 2,139 listings, the shorter one uses 873. The smaller list will block out the majority (probably over 98%), perhaps the odd one will slip through. (The full list excluded partial ranges that were smaller than a total of 256 addresses. The shorter list excluded ranges of 8,192 addresses or smaller.)

(Remember this list is only a country block, not a spam host block list. But it will have a similar effect since a significant percentage of spammers and bad clients do come from the two countries in question. And for those whom have been asking, it will enable you to get search results more regionally.)

If you find it confusing, just ask.

Scroll to bottom of the document and copy all the addresses listed after the BLACK_LISTED_IP_ADDRESSES=

Then paste them into the equivalent location in the limewire.props file. Or at the end of any banned address listings already there would be best. Make sure there's no spaces or carriage-returns before the numbers after you paste them in.
You might not see the .props extension on the file in the LW preferences folder. But if you get the file's properties, it will say it's a props file.

Edit: Just discovered if you have never previously banned hosts then the black listed ip address section will not show in the props file. Though I imagine most people have banned hosts. I've amended the instructions just in case of that scenario. ie: in that scenario, copy the Black_listed_ip_addresses= as well as the numbers as an entire paragraph into a new line at the end of the props file.

I've edited the file several times after some errors and some LW fussyness, I think it should be as good as it can now. Apologies. uh, maybe I should quit.

Edit: I have provided an installer to do it all for you for MacOSX users. ie: simply run the installer once and it will place the block list exactly where it needs to be whether you have a previous ban list or not. The installer is only for MacOSX users. Warning: do not run the installer more than once, it's a large list so you do not want double that. The applescript does it all in 1 or 2 seconds or less, takes fraction of a second on my computer (when you see the Quit menu, it has finished.) If you have a previous ban list then this list will be inserted at the beginning. If you have no ban list, the installer will insert one at end of the props file. LimeWire must be closed before you run this installer.

Edit: installer no longer needed, so has been removed.
The list updated to correct a few minor items of formatting and removed instructions for adding to LW. Re-attached in case anybody wishes to use for firewall blocking. For other purposes, the security list should be used instead. Firewall listing will reduce pings directly on LW and thus less chance of lagginess after multiple day long sessions.

(Attachment removed, needs updating anyway as the ipv4 addresses had not yet finalised in 2012.)