OSEC

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Subject: Re: smtpd_helo_restrictions not being honoured
From: Rudi van Houten (R.vanHoutenmath.uu.nl)
Date: Thu Aug 17 2000 - 06:38:09 CDT

On Thu, Aug 17, 2000 at 11:14:45AM +0000, Ralf Hildebrandt wrote:
> On 16 Aug 2000 18:52:16 +0200, Michael Tokarev <mjttls.msk.ru> wrote:
>
> >This is the smtpd_delay_reject = yes parameter.
> >If it is set (the default), any rejection will be delayed
> >untill RCPT TO will be issued.
>
> This way you can gather useful information about the crap they're trying to
> send and ...
>
> > If you set
> >smtpd_delay_reject = no (as I did), then negative answer
> >will be issued immediately, namely:
> > right after connect, for client_restrictions
> > after HELO/EHLO, for helo_restrictions
> > (or after first command _not_ HELO/EHLO, if
> > smtpd_helo_required also set to yes)
> > after MAIL FROM, for sender_restrictions, and
> > after RCPT TO, for recipient_restrictions.
>
> ...even the dumbest spammailer will accept a 5xx error after RCPT TO: (some
> try again if they get rejected right at the connect)
>

Some spammers even go on sending after postfix sent the 5xx error
in reply to RCPT TO:, I think the spam program does not look at the
reply codes. 

-- 
Rudi van Houten	  Department of Mathematics Utrecht University
Budapestlaan 8  -  3584 CD  -  Utrecht  -  Netherlands
:-) Fantasy is given mankind to make amends for what he is not,
    and a sense of humour as consolation for what he is.