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Re: [Asrg] Please critique my anti-spam system

2004-12-05 15:02:43
At 4:04 PM -0500 12/5/04, Michael Kaplan imposed structure on a stream of electrons, yielding:
[...]
There seems to be some concern that this system will effectively
'Joe Job' innocent people.  I don't see the clear incentive for
spammers to do this - why not just use a forged address?

As a somewhat tangential note, I think 'joe job' is a bit overbroad in this context. Its origin was a very conscious, intentional, targeted, and successful attempt to smear a hosting provider who had kicked the particular spammer off of his service. That sort of attack is pretty rare.

What is very common is simple random forgery of working addresses. I'm not convinced that most spammers have thought this through well, but at this point I think most of them have figured out that the envelope sender's domain had best be resolvable to a plausible path for mail delivery, because it is very easy to reject mail without that. More recently some unwisely managed mail systems (such as Verizon's) have taken up the dangerous practice of blocking inbound SMTP sessions while they confirm that the offered envelope sender is acceptable to a machine that would have to accept mail for it. This sort of ill considered 'verification' has led to an environment where using fully bogus addresses is somewhat less functional than using fully functional ones, but the last thing that the low-end spammers want to do is provide their own working addresses.

I don't
personally know anyone who was Joe jobbed.  Is this that common?

In the random forgery sense, it is extremely common. However, the way most forged-sender spam is send and rejected these days pretty well hides the extent of that problem from most users, because most of the spam that is rejected is rejected in SMTP at the exterior MX for the target domain, and only the spammer's own SMTP engine sees the rejection, not some real SMTP client that will bounce the rejected message. There are still a lot of exceptions to that in absolute numbers, but not so much that most people whose addresses have been forged will ever know about it.

The idea that ANY email address which is actually used can be kept secret from all spammers is fundamentally flawed. As long as people are dumb enough to use Windows and other people continue to mail them, email addresses will leak to spammers, because the low end of the spammer genus has effectively become one with the swarm of malware authors who prove daily how bad MS-ware really is.

Also if spammers know your address then you can solve the problem by
activating my system and using a sub-address.

There's no need to use a system with an intrinsically abusive C/R aspect and/or the text-hostile CAPTCHA model to use tagged addresses. For example, I'm on my 4th special address used only for posting to this mailing list. The prior 3 all have had spam (and malware) directed at them as a result of what appear to be innocent fools reading this mailing list.

--
Bill Cole
bill(_at_)scconsult(_dot_)com


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