> Actually, there is one reason to consider it stupid: I might have > control over my forward tree, but not over the reverse tree for the > IP address I have.
But, as I understand it, that is *exactly* the datum that people who use the reverse tree for spam detection are interested in. They want to know whether or not you have control over your reverse tree. If you don't, then the odds that you're a fly-by-night operator are somewhat higher than if you do. > That doesn't mean I'm a spammer - it just means I have a lousy ISP. Spam mitigation is obviously an uncertain business. But if something is empirically found to be a useful clue (amid a constellation of other clues), then it'd be foolish to ignore it. I'm not an expert on spam mitigation, but I've talked to people who are, and been told that reverse DNS is one of the two or three most useful tools in their toolboxes. That's not just made up out of nothing (as Dean Anderson seems to be alleging in his draft); it's based on real empirical analyses of spam trends, and rates of success and failure at filtering. Now, clearly, there are no immutable laws of nature here. Sources of spam change over time; perhaps by 2009 or 2010 it will no longer be useful to test whether a reverse tree is populated. (Indeed, the more useful a test *is* at rejecting spam, the stronger the pressure for spammers to find a way to pass the test. The half-life of useful tests is probably pretty short.) All I know is, right now in 2007, people I consider both trustworthy and knowledgeable tell me it's useful, and quote statistics to back the claim. (There are high-traffic mailing lists on this very subject: have any of them been consulted about this? I'd be interested in their take on the matter.) -- Evan Hunt -- [EMAIL PROTECTED] Internet Systems Consortium, Inc. _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www1.ietf.org/mailman/listinfo/dnsop
