Maintaining a whitelist

Vernon Schryver
Mon Jul 23 14:33:03 UTC 2001

> From: Gustav Foseid <>

> ...
> Qmail works the same way even for local delivery. If you send a message to
> "DoesNotExist@QmailControlled.domain" you will receive a bounce message
> from Qmail at the remote end. The message will be accepted at SMTP level
> and a bounce message will be delivered by Qmail.

I did not realize that Qmail is so badily broken and non-compliant
with RFC 821 and RFC 2821.

> ...
> You can build a list of the recipients as you receive the RCPT to commands.
> After the DATA command you can either reject the message, if none of the
> recipients should receive the message, or accept it, if all or some of the
> reciepients should get the message. After the message is accepted, a bounce
> message for the recipients that did not receive the message should be sent
> (this would have to be done by dccm).
> I do not know if this is possible with milter.

Milter simply allows you to add code to the middle of sendmail without
hacking on sendmail.  There is still code running on a corporate
gateway I controlled until a few years ago that does body filtering
somewhat similar to the way dccm works.  I modified sendmail itself.

It would be a bad idea for for dccm to try to originate non-delivery
messages or bounces.  It's not just the hassle of fork()'ing a process
to talk to sendmail to send the bounce.  It is that in practice many
and usually most of the bounces would not be deliverable and would
themselves generate double-bounces which would land in the postmaster

Vernon Schryver

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