Yes, the problem with blacklists is that they block tons of legitimate mail and do next to nothing to stop spam. The PMEB has been blacklisted off AOL and several other large ISPs at various times. There was a period about five years ago when Steph and I spent large chunks of time writing to ISPs and explaining that we are a legitimate, subscription mailing list. (Somehow, we haven't had that problem in a while.)

The *only* effective spam control measure is the "challenge/response" system. This involves each user developing a "white" list of addresses that will pass through unchallenged, and anything from someone not on the list is "challenged" (a message is sent back to the sender to verify that it's a human being, not a spambot before the message is delivered).

The time has come to blacklist blacklists!

Blacklisting is actually a very effective way to stop spam; it's just important that it is set up correctly and an accurate set of blocks are used. There are dozens of sets of blocks out there - as you say some block (tons) of legitimate mail, but they do however generally stop a great deal of spam.

I currently use spamhaus.org's block list, which as I am aware has a very low false positive rate, but blocks several dozen spam a day for me. For the few positives (1 a year) I have a webmail form in the bounced email for the user to contact me.

The fact that you get a bounce with DNS blacklisting is the great thing about DNS blacklisting - at least you know you've been identified as junk. With other methods of stopping spam - a junk mail folder - you don't know you've ended up there.

Like I say though (as with anything) it is important it is used correctly. That includes taking off false positives quickly, and having careful methods as to how IP addresses get on the lists, and this is all down to the provider of the list.

Challenge/response systems are a nice idea, but they also have the own set of problems. See http://www.politechbot.com/p-04746.html (http://www.politechbot.com/p-04746.html).

It's only going to get worse. I think e-mail is on its way out, believe it or not. A useful tool has been ruined by the darker forces in the universe, and it's too late to put that genie back in the bottle. E-mail is just going to get too unruly, and someone is going to have to write the new killer app to replace it.

Admit it...you and Jeff are Kiwi Spammers! ;)
The spam has dropped off a lot...sorry it's getting my mail from friends :P

We'll see what Paradise say :)