On Mon, Jul 12, 2004 at 12:31:00PM -0700, Steve Lamb wrote: > David Fokkema wrote: > >> - The math for C-R simply doesn't scale. > > > ? > > I'm not sure what Karsten had in mind here but let me give my first hand > view on this piece. My current employment gives me access to TMDA in > production use. In one instance a client of ours gets over 9,000 messages *a > day*. Virtually all of it is spam. They have configured TMDA to C-R. So > follow the math. > > 9,000 messages a day for 14 days (default pending queue) is 126,000 messages > in the pending queue at any given time. I believe this is a modified maildir > format. Not pretty. > > 9,000 challenges sent out a day. Most of which are to invalid addresses. > Those that aren't are sent to an innocent 3rd party. > > Close to 9,000 bounces generated a day thanks to the above challenges being > sent out. > > So for an initial investment of 9,000 messages we've generated close to > 18,000 more, all of which are worthless but need to be processed. Those are > tons of connections going out, loads of logs being written. CPU time wasted, > hard-drive space taken up. And that's just one client with a modest number of > addresses (5-6?). > > C-R does not scale because in its best implementation, barring any other > filtering, is an n*2 (spam + challenge) and often is a n*3 solution (spam + > challenge + bounce). As the spam problem gets worse C-R compounds it. > > Mind you that the offical TMDA party line might be to use it as part of a > grander scheme but some people have come here to this list to tell those of us > with a little clue that C-R (in particular their broken implementation, not > TMDA) was far superior than spam filtering and that spam filtering simple was > not needed and a waste. > > C-R works best when integrated into a larger spam-filtering solution. IE, > any marginal message within a narrowly defined statistical range would get a > challenge. Anything below that narrow range is passed through. Anything > above is rejected. But as Karsten has pointed out at that point what's the > point since filtering is doing virtually all the work anyway? > > Filtering does not compound the problem. Filter those 9k messages and > reject most at SMTP time you've only had to process.... 9,000 messages. Not > 18,000. Not 24,000. 9,000.
Got it, thanks! David -- Hi! I'm a .signature virus. Copy me into your ~/.signature to help me spread! -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]