* Martijn de Munnik <mart...@youngguns.nl>: > 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.
Do you have a caching DNS server? > The to address is an unknown user on my system so postfix could return a > 550 error. How can I do this? Reorder the checks > relay_domains = $mydestination, slagenlandwonen.nl, wfcommunicatie.nl, > gooischebrink.com, interjute.nl, melamo.nl, fair-play.nl, loopbaankamer.nl, > ospl.nl, ospl.de, printcontrol.nl, dankers-schilderwerken.nl, promonta.nl, > interim-denbosch.nl mydestination, is not a relay domain! > smtpd_client_restrictions = reject_rbl_client dnsbl.njabl.org, permit Does this one still work? > smtpd_recipient_restrictions = permit_sasl_authenticated, > permit_mynetworks, reject_non_fqdn_recipient, reject_non_fqdn_hostname, > reject_non_fqdn_sender, reject_unauth_destination, > reject_unlisted_recipient, reject_unknown_recipient_domain, > reject_unverified_recipient, reject_invalid_hostname, reject_rbl_client > virbl.dnsbl.bit.nl, check_policy_service inet:127.0.0.1:12525, > check_policy_service inet:127.0.0.1:10023, permit Your problem is that you distributed the checks all ocver smtpd_sender_restrictions, smtpd_recipient_restrictions and smtpd_client_restrictions > smtpd_sender_restrictions = permit_mynetworks, > reject_unknown_sender_domain, permit -- Ralf Hildebrandt Geschäftsbereich IT | Abteilung Netzwerk Charité - Universitätsmedizin Berlin Campus Benjamin Franklin Hindenburgdamm 30 | D-12203 Berlin Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962 ralf.hildebra...@charite.de | http://www.charite.de
