http://blogs.msdn.com/tzink/archive/2009/06/30/my-take-on-blacklists-part-2.aspxI'm going to attempt to summarize a blocklist without going to the article on Wikipedia.&#160; I'll be doing this straight off the top of my head. Motivation A blocklist is essentially a shortcut to spam filtering.&#160; Assume that you have a contentenCommunityServer 2.1 SP1 (Build: 61025.2)http://blogs.msdn.com/tzink/archive/2009/06/30/my-take-on-blacklists-part-2.aspx#9822861Tue, 07 Jul 2009 19:13:26 GMT91d46819-8472-40ad-a661-2c78acb4018c:9822861mbghtri<p>What about botnets? I assume that one of the reasons for the quantity of botnet spam is that blacklists are less effective when you are dealing with hundreds of thousands of unique IPs.</p> http://blogs.msdn.com/tzink/archive/2009/06/30/my-take-on-blacklists-part-2.aspx#9827736Fri, 10 Jul 2009 01:17:34 GMT91d46819-8472-40ad-a661-2c78acb4018c:9827736Sabre<p>mbghtri said: &nbsp;</p> <p>&gt; What about botnets? I assume that one of the reasons for the quantity of botnet &gt; spam is that blacklists are less effective when you are dealing with hundreds of &gt; thousands of unique IPs.</p> <p>Which is why people use the Spamhaus PBL, it nails most of the botnet spam. Go check it out: <a rel="nofollow" target="_new" href="http://www.spamhaus.org/pbl/">http://www.spamhaus.org/pbl/</a></p>