> SMTPACL is attempting to expand the use of mailets, which are already
> heavily tied to SMTP processing, to a faster-fail environment.

Agreed.

> > I would permit something like:
> >
> >   <filter event="<event>">
> >   </filter>

> This implies there are more protocols and events than we actually have.

No, just more events, e.g, connect, HELO, MAIL FROM, RCPT TO, DATA.  I am
not pre-supposing which ones are useful, or even for which ones we will
implement a filter processor.  I simply proposed a syntax that would permit
a consistent treatment in the future.

> >   <filter event="<CONNECT>">
> >     ... DNS RBL checks ...
> >   </filter>

> This doesn't really relate to the mailet API, instead to our
> server-container.

Why?  We already have a DNS RBL matcher which provides this functionality.
This just permits it to provide it as a fast-fail at the earliest time.

> Are we sure this is legal for a mail server to reject this way,
> except temporarily such as responding to a DOS attack?

Yes.  See RFC 2821, section 3.1.  We would return a 554 instead of a 220,
return 503 for any commands other than QUIT, and wait for the client to
issue a QUIT before disconnecting.

And if one wants to configure one's system this way, and avoid being listed
in the RFC ignorant RBL, you need to provide a very specific message
regarding why you are rejecting the connection
(http://www.rfc-ignorant.org/policy-postmaster.php).

> > Leaving the choice of what and when to the mail admin, or possibly
> > some future RFC.

> Yes, this is about giving the mail admin choices of fast-fail.  But
> you're suggesting a solution to give RFC authors choices.

No, as noted above, I am proposing a general syntax so that we have a
consistent approach to whatever we need to do in response to evolving mail
RFCs or user requirements.

> > And, just as a talking point, I think that we may want a Mailet
> > that explicitly provides a return code and message so that we
> > can better collect statistics.

> I believe that was addressed.  If you mean to separate the two pieces
> of data, then you've hardcoded responses to how SMTP handles responses.

I am saying that there ARE cases where it is important in the protocol state
machine to know what responses have come before.  If you issue a 554 in
response to a connection, it carries implications for future processing.  I
don't want to have to parse the response string.

In any event, I don't see this as something we need to hash out right now.
:-)

        --- Noel


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