Paul Graham Describes Dangers of Spam Blacklists

CRoby writes "Paul Graham posted an essay describing the danger and corruption of the main spammer blacklists today. It discusses MAPS and the SBL, the blacklist created to try to alleviate the abuses of MAPS, and suggests (maybe) another blacklist's creation."

Comments

Guideline, not a rule

[bitflip]

I use blacklists all the time. Rather than simply rejecting the mail, if the server is on a blacklist, the initial OK is delayed by five seconds.

If you're sending a ton of mail, i.e., spam, little of it gets through. If you're only sending one or two messages, ie, likely legit mail, it goes through just fine.

Combined with more specific stuff further back (bayes, et. al), it's been quite effective at reducing the amount of spam sent, and the amount of mail that gets scanned.

The problem isn't blacklists, its how people use them.

"Power-hungry weenies"

[slavemowgli]

Interestingly enough, the owner of the acme.com domain who was recently featured in a story due to his getting more than a million spam mails (well, attempts to send spam) a day, agrees:

DNS-RBLs - Domain Name System Realtime Black Lists. In theory the idea is fine. You have a set of sites that you blacklist, and you want to let other folks use the same list so you distribute it using DNS, which is a nice efficient de-centralized database. What's not to like?

Well, I don't know why, but in practice every single DNS-RBL eventually comes under the control of power-hungry weenies. They start listing sites unreliably, and if you complain you find yourself listed. And there's usually no way to get off the list.

A lot of people tell me I'm wrong about this. They say that certain DNS-RBLs are ok, with objective criteria for inclusion and simple procedures for getting off the list. The thing is, they give conflicting recommendations for which lists are good and which are bad. Some of these folks recommend lists which I know from personal experience are bad.

This problem is really inherent in the way DNS-RBLs are set up. You cede control of your mail system to a third party, with no real possibility of checking how they are doing. The people running the lists get overwhelmed with bogus feedback from spammers and/or idiots, to the point where they assume all their mail about the lists is from spammers and/or idiots.

If the lists you use have not yet descended into corruption and chaos, consider yourself temporarily lucky.

Do not use DNS-RBLs.

(from http://www.acme.com/mail_filtering/shame_frameset. html)