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Subject: Re: Is this possible with postfix?
From: Craig Sanders (castaz.net.au)
Date: Fri Mar 03 2000 - 19:30:15 CST

On Sat, Mar 04, 2000 at 12:39:25AM +0100, Daniel Roesen wrote:
> > The internal client should never bypass its assigned SMTP host,
>
> Not all internal clients have an assigned smarthost. All UNIX systems
> I know deliver Mail according to DNS MX information by default.

but they can all be configured to use a smarthost. at least, any unix
MTA worth using can...and it can be done quickly and easily - usually
just a few seconds work with vi.

> > Replace internal client with "Outlook Express" and set its SMTP
> > server to be "Internal SMTP" in its config.
>
> OE is LIMITED to smarthost usage. Unix boxes generally NOT.
>
> > It shouldn't where the mail is going, all outgoing mail from Outlook
> > Express will go through Internal SMTP.
>
> Indeed. But the world has more to offer than crappy Win MUAs.
>
> You CAN setup ALL internal hosts to use a smarthost, but I think this
> is not the preferred way to handle it. YMMV.

it's the way i'd set it up. all internal hosts configured to use the
internal smtp relay.

if my router/firewall could do packet redirection (i.e. "transparent
proxying") then i'd also set up rules to catch outbound port 25 packets
and redirect them to the internal smtp server.

if not, then i'd just block (packet filter) outgoing port 25 packets
from the internal machines - the client machines either use the
smarthost or they don't get any mail delivered. end of story.

(there may or may not need to be some exceptions to the blanket redirect
or block rules, depending on whether you have some internal machines
which need to send mail direct to the net. most likely not)

craig 

--
craig sanders