To: Keith Moore <moore@cs.utk.edu>
Cc: Harald.T.Alvestrand@uninett.no, drums@cs.utk.edu
Subject: Re: support for Postmaster address 
In-Reply-To: Your message of "Thu, 05 Oct 1995 17:05:39 -0400."
             <199510052105.RAA02108@wilma.cs.utk.edu> 
Date: Fri, 06 Oct 1995 14:32:57 +1000
Message-Id: <22867.812953977@munnari.OZ.AU>
From: Robert Elz <kre@munnari.OZ.AU>


    + for any SMTP host that receives or relays mail, 
    <postmaster@fqdn.for.that.host> and
    <postmaster@[any-ip-address.of.that.host]> must
    be valid and reachable addresses,

No, that, while it might be nice, isn't practical really either.

Consider a stateless mail relay (no stable storage), that has
an internet (ethernet, anything) on one side, and x.25 (or
something) on the other side, and whose whole purpose in life
is to take smtp mail and relay it to X.400, (and vice versa).
For now assume there is some point to doing this...

This box takes incoming smtp mail, does some kind of directory
lookup (over the net) to determine the appropriate X.400 address
corresponding to the smtp addr (or it could be in /.../ blather
format making this even easier), when it gets each RCPT command,
rejecting any it cannot convert, then it opens an X.400 connection
to the recipient(s) (as many as needed, all in parallel), and
as it takes the data (after DATA) converts the format on the fly
pumping through the message, including adding X.400 trace fields.
When it sends its response to the '.' following DATA it is done
with the message.

That's all it does (for now assume this is possible, if not for
X.400 it is for other mail relays) - it has no discs, no way for
users to login, no mailboxes, at all, ...

For outgoing internet mail it does just the same, including adding
its Received header.

Does this box really have to have a postmaster?

I know the way it would be implemented would be to MX its name
to some other host, and support postmaster on that, but is it
really required?   This box to me is basically the same thing as
a terminal server or router, no-one should ever be sending any
mail addressed to it, for any reason, ever.

Before we decide on rules for having postmaster support on
everything in the known universe, we should probably decide on
just what benefit we expect to achieve from that - ie: make a
statement on why postmaster support is required, beyond "the rules
say so".  Knowing just what we are achieving will make it much
easier to decide exactly what we have to do to achieve it.

While we're doing that, do bear in mind that as mail people, we
tend to assume that postmaster is the beginning and end of all
problem resolutions - it's not.  Depending on the problem, assuming
some postmaster somewhere can help is not necessarily wise.
Eg: if a host isn't properly handling mail it is being sent
because of an MX aimed at it, asking its postmaster might be
useful, or might not.  The correct person to ask there is the
person who made the MX point that way - they will know if the
MX is corect, in which case they can get the responsible person
to fix the broken mailer, or if the MX was just an accident.
That person's addr is found in the the SOA record of the DNS zone
in which the MX record was found.   That's where the initial
enquiry should be directed in this case.

kre