On Tue, 18 Feb 2003, Dave Hart wrote: > > From: Hugo van der Kooij [mailto:hvdkooijat_private] > > Sent: Tuesday 18 February 2003 06:48 > [...] > > If a message is undeliverable it will be bounced BUT if the > > bounce message > > can not be delivered it will be discarded immediatly to > > prevent double > > bounce loops. > > > > See also RFC 2821 section 4.5.5 > > Would you care to cite where it's said that NDRs and other MAIL FROM:<> > messages must be discarded immediately if the first delivery attempt > fails? The various mailers I have used continue to retry transmission > until configured timeouts, as with any other outbound message. When the > mail is an NDR being sent to a bogus domain (such as in response to spam > with a forged sender email), it does clog up the queue for that timeout > period. From 4.5.5.: Implementors of automated email processors should be careful to make sure that the various kinds of messages with null reverse-path are handled correctly, in particular such systems SHOULD NOT reply to messages with null reverse-path. But the problem arises before that. If your server is set to accept message for non existing accounts you have a server that can be easily brought down. If you do not accept these messages you do not have to send bounce messages. It will the task of the system that tried to hand them to you. If you find yourself with a server with lots of waiting bounces your are likely (ab)used as relay and you have other fish to fry. And from 6.1: When the receiver-SMTP accepts a piece of mail (by sending a "250 OK" message in response to DATA), it is accepting responsibility for delivering or relaying the message. It must take this responsibility seriously. It MUST NOT lose the message for frivolous reasons, such as because the host later crashes or because of a predictable resource shortage. Which seems to indicate you have to make sure your mailserver is up to the task. Hugo. -- All email sent to me is bound to the rules described on my homepage. hvdkooijat_private http://hvdkooij.xs4all.nl/ Don't meddle in the affairs of sysadmins, for they are subtle and quick to anger. ---------------------------------------------------------------------------- This list is provided by the SecurityFocus ARIS analyzer service. For more information on this free incident handling, management and tracking system please see: http://aris.securityfocus.com
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