[LINK] Spammer trick could send junk email soaring

[Chris Maltby]

On Tue, Feb 08, 2005 at 10:41:30PM +1100, Karl Schaffarczyk wrote:
> <snip>
> >ISPs who don't filter spam on outbound mail will get blacklisted.  ISPs 
> >that
> >do filter won't.  problem solved.
> >
> >this isn't a bad thing at all.  it's a good thing.  it will force even lazy
> >and indifferent ISPs to take responsibility for the garbage that their
> >windows-using ignorant menace customers are spewing out on the net.
> 
> <snip>
> 
> This type of system is fine until you encounter an ISP such as bigpond.
> 
> If bigpond makes it to a blacklist (and often, they do, and for good 
> reason) the complaints, and loss of customers is worn by a smaller 
> ISP who is doing the blocking. ("my friend who is with bigpond cant 
> send me email, but they can send it to everyone else")
> This reflects the current situation - if bigpond customers are 
> sending out thousands of pieces of spam per day, then its the smaller 
> ISPs problem. If the smaller ISP customers are sending out spam, then 
> it's the smaller ISPs problem.
> 
> It hardly seems fair.
> 
> Worse, it means that providers such as bigpond just dont care, and 
> will continue to have customers who spam (either through security 
> holes, or by means of their customers deliberately spamming).

This is what's wrong with address blacklisting too simply.  The lists
are too coarse grained to be useful as an on-off email switch. But
tools like spamassassin can use the RBL lists to add spam points to
messages which have come via a suspect relay - but not enough to flag the
message as spam unless it matches some of the other rules as well.

Chris