Re: Spamcop listed - need help to diagnose why

[Ceri Davies]

On 8 Jan 2006, at 05:03, Ted Mittelstaedt wrote:

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Robert Slade
Sent: Friday, January 06, 2006 11:24 PM
To: David Banning
Cc: [EMAIL PROTECTED]
Subject: Re: Spamcop listed - need help to diagnose why




address and all programmes such as TMDA do is send a challenge to an

an hour it is quite easy to report 1 my accident. If you look at the



and use a combination of spamassassin and block lists.

BTW I make it a point never to respond to challenges.

There is your problem TMDA is most likely the cause. Such programmes are in effect adding to the spam problem. Nearly all spam has a forged from innocent 3rd party. Whist it looks like it reduces your spam all you do is in effect spam someone else. When your e-mail address has been used in a spam run by a spammer and you start getting 10s of these challenge Spamcop reporting page you will see a warning about just this situation. I suppose that the real answer is to stop compounding the spam problem

Ditto, and for the same reasons.  I've removed David from the cc
list on this for that reason as well.

Also we need to be aware of another trick that spammers have
figured out, that applies to anyone running multiple MX records on
a domain (I don't know if David is in that situation)

Normally if a domain has a single mailserver processing incoming
mail, there's a single MX record pointing to a single machine.   But
in many cases it's desirable to relay mail through a prefilter system
before it gets to the actual mailserver.  In those cases a common
trick is to block the highest priority MX host off with an access
list.  Senders try the highest priority, it fails, they then go to
the next highest priority host which is the relay host.  That host
gets it, does it's thing, then tries to send it to the highest
priority server which should work since the access list permits that
server.  This technique has been mentioned in the sendmail book
among others.

Ceri

Yes, but that is actually massively rude. The hosts listed in a domain's MX record are supposed to be hosts willing to exchange mail for that domain, so listing ones that are not it just wasting everyone's time and resources. If you want to have such a prefilter system, there is no need to list the end system in the MX records; just use an internal route to do that.

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