Re: Rejecting during smtp

On Fri, Apr 29, 2005 at 08:54:49AM -0400, Martin wrote:
> One of the big issues with challenge-response is that the challenge goes to 
> often fake email addresses and 'harasses'  innocent people.  Some people even 
> treat it as spam.

So be it, I do not agree with those people, delivery notifications are a
good thing, mail servers _always_ should send bounces if mail cannot be
delivered to the recipients
 http://marc.theaimsgroup.com/?l=qmail&m=111314493525750&w=2
 http://article.gmane.org/gmane.linux.debian.user.isp/8124

> There are qmail patches that will hold the smtp connection open, check if the 
> user exists, and do a rejection at that point.  Blacklists do the same even 
> putting in the blacklist information and code.
> 
> How about changing qconfirm to do the same ?
> 
> ie. During the smtp transactiion, hold the connection open, check to see if 
> they are in the whitelist, if not, put the challenge email address in the 
> rejection so the user can email to that challenge and get whitelisted.

This suggestion is similar to how subscribers-only mailing lists work
today, compare that with subscribers-only mailing lists with a qconfirm
setup for non-subscribers.  qconfirm's technique adds convenience for
users, sender as well as recipient, as it doesn't require the mail to be
re-sent.  With qconfirm a mail from an unknown sender is accepted to the
local qmail queue (MX takes responsibility for this message), but local
delivery is deferred.  If delivery finally is not possible because no
delivery confirmation has been received, a bounce is generated (as per
the responsibility).  So, no, I don't think this is a good idea, better
try to teach the people how to deal with delivery notifications caused
by mail with forged envelope.

Regards, Gerrit.