Re: [Exim] Example of legit email rejected by testing on rev…

Top Page
Delete this message
Reply to this message
Author: Jason Robertson
Date:  
To: exim-users
Subject: Re: [Exim] Example of legit email rejected by testing on reverse IP lookup
I know 64/8 and a lot of other /8's are blocked at various stages.. In
my spam filters many networks are listed as bad, though I do not
necessarily block them, they are part of my overall filtering scheme.
As an example all dsl, ppp/slip, cable, ips are held to higher level of
clean emails, to reduce the spamming, though Ideally no one should be
using their personal connection to send directly to the end machine.

If you want to run your own site of a dsl line, go out and spend the
extra money at get a dedicated business line. Here in Canada it would
only run around $100/month for a 3M DSL, for you 'mericans that's
around $65ish/month

The problem I have noticed with any of these IP blocks used by
DSL/Cable/Dialup providers for residential, is that there is often a
great deal of spam associated with these, because of silly
misconfiguration or deliberate use of the service, especially on the
larger providers that do not have the manpower to handle the number of
complaints, when I was an admin of an extremely small ISP(<5000 user),
we would get 4/day, which I would handle after hours.. But in larger
ISPs admins don't do that because they would never get home (though
some days I didn't get home).

Anyways I should get back on topic, it's because of this, that many
sites block some blocks period 64/8 I know though is on my groups of
network blocks that I monitor. 65/8, 66/8, 24/8, I could keep going.

Anyways my 2 cents or maybe it's 2 pence.

jason

On 8 Dec 2002 at 11:30, Giuliano Gavazzi wrote:

> At 16:22 +0530 2002/12/08, Suresh Ramasubramanian wrote:
> >On Sun, 2002-12-08 at 16:13, Matthew Byng-Maddick wrote:
> >
> >>  > It means - you are in a customer IP block, most likely dynamic
> >>  > IPs. So, he is asking you to set up your exim to smarthost through
> >>  > your provider's mailserver.
> >>  > > <h-64-105-159-234.PHLAPAFG.covad.net[64.105.159.234]>:
> >>  > >     Client host rejected: mail from domains with
> >>  > >     generic/dialup/DHCP
> >>  > > addresses is not accepted - contact your ISP for support

> >>
> >> Yes, indeed.
> >>
> >> Smarthost through your provider.
> >
> >As long as the IP is static I have no problems with accepting mail from
> >that netblock in general (except in cases where there is more than a
> >few spam sources from a single /24 of such IPs).
> >
> >Dynamic IPs on the other hand deserve to be blocked wholesale. Ditto
> >with NAT gateways like some idiot cablemodem providers run (allotting
> >their users RFC1918 addresses and NATting all outbound traffic through
> >one or more IPs).
> >
> >    srs

>
> the same here, I would not have blocked the above if the HELO
> argument had been in the same domain as the reverse lookup, after all
> what's the point pretending to be something else since that is what most
> spammers but very few bona fide servers do?
>
> Giuliano
> --
> H U M P H
>     || |||
>   software

>
> Java & C++ Server/Client/Human Interface applications on MacOS - MacOS X
> http://www.humph.com/
>
>
>
>



--
Jason Robertson
Now at the Nation Research Council.