From: Firebeard <stend+cypherpunks@sten.tivoli.com>
Date: Tue, 8 Jul 1997 13:27:52 +0800
To: cypherpunks@ssz.com
Subject: Re: ISP signatures on outgoing mail
In-Reply-To: <3.0.2.32.19970704104000.006ba75c@popd.ix.netcom.com>
Message-ID: <vpd8ouyv8j.fsf@sten.tivoli.com>
MIME-Version: 1.0
Content-Type: text/plain



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>>>>> Bill Stewart writes:

BS> At 06:14 PM 7/3/97 +0200, Anonymous wrote:
>> Anyone heard of a proposal for ISPs to automatically sign outgoing
>> mail headers?  Problem has been that spammers send email by one
>> path but forge a reply-to or from address at another location.

BS> Flat-out can't work.  The problem is that you can send SMTP
BS> directly from your machine to its destination, so the ISP only
BS> routes the IP packets and doesn't read them.

	But it could - it's simple firewall technology.  There's no MX
record for sten.tivoli.com, but any incoming email to me is
intercepted by proxy.tivoli.com, as is all other incoming traffic to
the internal tivoli.com network on port 25.  Since 'incoming' is only
a matter of definition, it would be trivial for an ISP to set up a
firewall that passed all other ports through transparently, but
redirected connections with a destination of port 25 to their own SMTP
server.

	I don't want them to, and I _certainly_ don't want the
government goons requiring ISPs to do this, but don't sit back and
relax with the notion that 'it can't be done'.

- -- 
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