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Re: rfe: automagic open relay message refusal?


Date sent:      	Thu, 14 Jun 2001 11:16:48 +0200
From:           	Arnt Gulbrandsen <arnt@gulbrandsen.priv.no>
To:             	zmailer@nic.funet.fi
Subject:        	Re: rfe: automagic open relay message refusal?

> Alexey Lobanov <aal@cpr.spb.ru>
> > 1. Seems, it is not an Unix Way. SMTP server should not generate 
> > outbound SMTP connections :-).
> That's not the "unix way". That's how it has to be.

By saying "unix way", I mean that a tool should do a single 
task, not many. Complex things are done by common work of 
several tools. "Say NO to Sendmail all-in-one daemon!" :-)

> Suppose that you run such a thing, and that you implement the SMTP
> timeouts exactly.

...as several hours, according to queue delays in an opened 
relay properly loaded by spammers of whole world :-). Note also 
that a lawful non-relaying MTA may freese unauthorized messages 
locally instead of instant rejection in SMTP dialog. Both MAPS 
and ORBS routines take it in account.

>  Suppose further that mumble.com does the same.  What's
> going to happen when you receive mail from mumble.com?
> When you see the RCPT TO, you'll open an SMTP connection to mumble.com in
> order to detect whether mumble.com's an open relay and when you say RCPT
> TO, that machine opens an SMTP connection to _you_ to check whether _you_
> are an open relay.
> At this point, the smart MTA realizes that it's already doing the test,
> and doesn't open a fourth connection. But what does it do?  What can it
> do?

Nothing good :-). The whole idea seems to be bad.


> --Arnt

Alexey Lobanov
CPR, St.Petersburg
Head, IT Department
Phone +7-812-3468247
Fax +7-501-3468248, +7-812-3271408
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