IP Banning turned back on again

For two weeks, I was logging incoming spam but not immediately banning the originating IP address. This greatly worked in my favor as each zombie system was shilling for several clients and by waiting a week or two, I was able to harvest a lot more domain names to block. What was especially inane of these id10t's is that they thought that if there were enough domain names in one spam, that maybe some of them would get through??? If I block for xyzzy.com and if xyzzy.com is in with 49 other URLs, #1) - it will still get blocked and #2) - those 49 other URLs will get recorded in the log file and also be blocked when I run the processing script. If anyone ever puts the authorship of comment spam program on their resume, I would not even consider them qualified to sweep my floors...