[Mimedefang] Another silly idea

[Steffen Kaiser]

On Tue, 2 May 2006, Paul Murphy wrote:

> Question 2: to what extent is your incoming spam volume generated by dynamic
> addresses, dial-up systems, broadband hosts, and other end-user systems which
> either have their IP address in their hostname (e.g.
> 220x218x25x21.ap220.ftth.ucom.ne.jp) or which resolve to names which indicate
> their dynamic nature (e.g. 53546EC2.cable.casema.nl)?  In my case, this is
> 95% or more of connections which are then rejected due to spam
> classification.

> Perhaps working on a system to list all valid mail servers would be a better
> idea?  This way, no end-user system can send e-mail out directly unless they
> are registered via a central registry which can then remove them for abuse.

> In other words, don't blacklist the temporary addresses which cause problems
> for a short period - whitelist those which are well behaved.

I hate this banning of dynamic addresses right away. Sure, there is no (at 
least not known to me) way to know, whether the host with a dynamic 
address is an badly or well configured end-user system, but this thinking 
cut me off several net projects, because I couldn't communicate with the 
project in a reasonable way anymore.
For one: If you want to use "roles" (e.g. use the Sourceforge mail address 
for projects hosted on SF.net, other ones for other projects a.s.o) the 
ISP must let the From field pass unaltered - actually I don't know one 
doing so without charging yet another fee.
Badly enough, the hoster of my personal mails started using a DUL black 
list and drops the connection during the initial connect - I even cannot 
use SMTP AUTH therefore.

There had been suggestions to add SPAM score points for dynamic hosts, 
which I would prefer and can see the purpose.

To implement a whitelist system for well-behaved MTAs includes the 
assumption that those have _fixed_ IP addresses; this need not be true.
I would at least give those poor people out there using a well-configured 
MTA on a dynamic address the chance to communicate with the world, e.g. 
using certificates.

Bye,

-- 
Steffen Kaiser