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Re: blocking dialups

  • From: "Clive D.W. Feather" < >
  • Date: Thu, 15 Oct 1998 09:11:02 +0100

torben fjerdingstad said:
>>  - Running Linux server with sendmail.
> Bad one. sendmail requires a fixed connection.


>> (1) You are then reliant on the ISP's mail server; if that breaks in any
>> way, you're dead in the water.
> I would feel a lot more dead if I had to waste phone costs retrying
> for days to do a delivery to santa claus, because his server is
> flooded.

Or you could do what I do on my dialup: run mail software that tries a
direct connection to the MX first, and falls back to the ISP mail server if
that fails.

> Note. Our mail server has been 100% reliable since I installed
> it on aug. 19. 1997.

How many millions of mails per day does it handle ?

>> (2) A closed user group can authenticate mail to addresses based on the
>> sender address; for example, I can email certain internal lists from my
>> dialup, but not everyone else can.
> I hope sender address means the ip address.


> Why would you want to
> be able to deliver those mails to us?

Who is "us" ? The point is, I can't afford to have those emails sent via
the ISP's relay, because then the sender's IP address will be wrong.

>> (0) I buy access to the *Internet* from my ISP, not access to their
>> intranet.
> I can't imagine how two dialup customers at that ISP can mail each
> other without a mail server at the ISP. Well, they could use pop3,
> but we are talking about smtp here.

Using SMTP. And we aren't talking about the inbound mail server, we are
talking about outbound relays.

>> Try:
> Since you ask I assume they are dialups. But they have not sent
> me spam, so I have no reason to block them.
> The directly sent spams I have seen came from large ISP's who have
> whole class C networks allocated for dialups. I'm not so worried
> about the rest of them.

At least one of the above hosts *is* a dialup on a large ISP who has whole
class *B* networks allocated for dialups.

Clive D.W. Feather       | Email: clive@localhost   | Tel: +44 1733 705000
Regulation Officer       | Home:  clive@localhost |  or: +44 973 377646
London Internet Exchange |                           | Fax: +44 1733 353929

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