[Mailman-Users] Trouble with mailman external responses

[vancleef at lostwells.net]

The esteemed Barry Warsaw has said:
> 
> Which ISP do you use?  I have a static IP from my cable company but  
> they refuse to give me an rDNS entry.  In every other way, I really  
> like them, but I do get bounces occasionally from people's (IMHO)  
> misconfigured MTAs who don't accept mail from cable rDNSs.
> 
> - -Barry
> 
Barry, I'm going to disagree with you on this one.  Virtually all of
the spam that gets through the various filters on my box comes from
big-service dynamic IP's right here in the US.  

Right now, I'm trying to home in on some of this spam, and am
operating under the assumption that I've got two or three users with
infected Microsoft systems sending out port 25 mail without their
knowledge.  I've pinned down a couple of others.  These users haven't
got the foggiest notion that there is anything wrong, what is wrong,
why it is wrong, or what to do about it, and that seems to be a common
affliction among consumer users with "always-on" internet
connectivity.

My own site has two IP's, with their own identities separate from my
upstream feed, with reverse lookups properly configured, and no port
blocking either way.  It took some time, discussion, and a couple of
very serious technical interviews with their people before they agreed
to that.  They consider me a "commercial" site "with competent on-site
administration," and terms and conditions which are quite different
from consumer sites.   

I'd really call a sendmail receiving site that blocks dynamic IP mail
as "misconfigured," when virtually all of the mail coming from such
IP's is spam.

Hank