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Re: Which Spam Block List to use for a network?

On Wed, Jun 23, 2004 at 10:26:49AM +0200, Adrian 'Dagurashibanipal' von Bidder wrote:
> On Wednesday 23 June 2004 09.51, Blu wrote:
> > I run a number of public service servers and in the past, from the
> > perspective of an user of a server which blocks mail from mine, the
> > mails were being blackholed at my host. They never got an answer or
> > even a bounce.
> Huh? Either your servers are/were severely misconfigured, or you don't 
> mean the same thing as I when you talk about blocking.
> block == reject with 5xx error code in the SMTP transaction. Or possibly 
> block at firewall level.

Yes, rejection with 5xx error, we are talking the same.

> So it's the task of the upstream mailserver to generate a bounce (and 
> since the upstream mailserver in most cases belongs to the 
> administrative domain where the mail originally comes from, there's 
> fair chance that the bounce actually gets to the sender of the mail.)
> How did your users not receive a bounce?

First, I live in a place where ISP mail servers are not trustable, so I
generaly maintain my own MX servers.

Until not so long ago, my MXs were accepting mail from hosts which were
themselves blocking mail from them. The result were that my
servers received mail normaly, but then they found that they cannot
answer. From the perspective of the remote user sending mail to my
server, the message simply disappeared because my users or even myself
had no means to inform the remote user of the fate of the message, at
least by email. Having mail driven automatic services, my mailbox was
full of complains and questions about the service being down, questions
which I cannot even answer because the MXs of those users didn't like

At present, rejecting those mails with an axplicative 5xx message, those
users at least (if they are able to read a bounce), know that it is not
my problem, it is theirs.


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