[NTLUG:Discuss] Postfix Spam Blocking

[Kenneth Loafman]

Kevin Brannen wrote:
> I'm curious what people think about challenge/response (C/R) for spam 
> control.  I can see it being fairly successful, but I can also see it 
> cutting down or eliminating real email from people you don't hear from 
> often enough to have whitelisted.  What are the thoughts of people on 
> this subject?

If you want to get yourself listed on an RBL, go ahead.  Spammers forge 
both the From and the Envelope From addresses, so if you C/R to one of 
those and its a spamtrap, then it gets reported and you get RBL'ed. 
Some will remove you, but some consider backscatter from the C/R to be 
more trouble than its worth, so they won't.

Also, make sure you read the backscatter HOWTO on the Postfix web site. 
  You do not want to even take a chance on bouncing mail to a spamtrap. 
  I know, because my corporate mail server started bouncing to spamtraps 
and we got listed for a bit.

http://www.postfix.org/BACKSCATTER_README.html

In my own personal opinion, C/R is a very selfish response to a problem. 
  It has too many issues to make it useful, and due to the spam problem, 
can cause harm (blockage) to the user.

....Ken