Michael Tokarev:
> > You're using WARN for debugging REJECT actions. A debugging warning
> > can be generally useful to alert that a restriction of some sort
> > would cause mail to be rejected. That is not limited to table lookup.
> >
> > And it's not difficult to implement either: the routine that
> > processes the "warn_if_reject" token has to manipulate a flag, and
> > there needs to be some code that maintains the flag appropriately
> > as code recurses and returns. Maybe the flag can be implemented
> > as a counter.
>
> Looking to this further, and having in mind several threads ("proper
> place for UCE restrictions", "Another interesting spam trick" with
> HELO argument validatio etc), I see a good reason(s) to have this
> sort of debugging very useful now... ;) And I see two variants for
> the usage. Dictinary lookup is unaffected by this, but other
> reject primitives are affected:
>
> a) smtpd_xxx_restrictions = warn_if_reject, reject_unknown_hostname
> b) smtpd_xxx_restrictions = warn_unknown_hostname

Something along the lines of a) is preferable, because functionality
is implemented in one place, while b) is a maintenance nightmare.

> o other "permits" can be made "tuneable" too either by prefixing
> a permit with "warn_if_permit" (or more general, warn_if_applicable")

And we would need a separate mailing list for discussions on how to
use this.

> o [what about header/body checks]

They need a WARN token; the present architecture allows us no choice.

If we had a bright moment then we could turn the whole UCE architecture
inside out, and change the existing test+reject code that is spread out
over smtpd+cleanup into a bunch of sensors for a policy daemon.

That is different from designs that copy the entire message stream
through some Kremlin-style censoring daemon, or that require that
all the test+reject be concentrated in the Postfix SMTP server.

> o with variant "warn_if_reject, reject", it is better to be able
> to use something like "warn_if_reject, 554 xxx" instead

The Postfix access control little language was not designed to
contain raw SMTP commands.

        Wietse
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