Martijn de Munnik wrote:
> Hi all,
>
> Sometimes our mail server is 'under attack' and we get a lot of these
> entries in our log file:
>
> Aug 17 11:08:19 stevie.youngguns.nl postfix/smtpd[14890]: [ID 197553
> mail.info] NOQUEUE: reject: RCPT from unknown[212.22.199.165]: 450 4.1.8
> <indispensabl...@homepc>: Sender address rejected: Domain not found;
> from=<indispensabl...@homepc> to=<banquetastrophys...@rpc-design.nl>
> proto=ESMTP helo=<homepc>
>
> Normally we reject about 15 msgs/min but when such an attack happens it
> peaks to about 700 msgs/min. The error is returned to the sending mail
> (spam) server is 450 domain not found. Because a domain lookup could
> also be a temporary failure this is a temporary error returned.
>
> The 450 error triggers the spammer to retry sending the mail.
>
> The to address is an unknown user on my system so postfix could return a
> 550 error. How can I do this?
>
> I've attached postconf -n output in main.cf.
>
> --
>
> Martijn de Munnik
>
I do not know your overall configuration.
However, you might consider using something like Fail2ban
<http://www.fail2ban.org/wiki/index.php/Main_Page> to stop the bad
traffic at your firewall.
just a thought
JLA
