>[I sent a similar message before to [EMAIL PROTECTED] and never saw it. I
>apologise if you've gotten this twice.]
It went through, and mine was the only reply, and it was several days
later. That's okay, I think both your and my messages are more organized
this time ;>
>I want to set up a two-tiered mail architecture, with a very high uptime
>qmail server at the top, and a less reliable exchange server below (I have
>no choice at all in the latter).
I run this setup. I prefer to have SMTP<->Internet done by qmail for
security, reliability, performance, and trackability.
>What I'd like the qmail box to do for incoming SMTP mail from the world is
>check to see if user is local, and if not, kick it down to exchange.
All easily enough done - the FAQ has an entry on this, as follows:
]How do I forward unrecognized usernames to another host? With sendmail
]I had a LUSER_RELAY pointing at bigbang.af.mil.
]
]Answer: Put
] | forward "$[EMAIL PROTECTED]"
]into ~alias/.qmail-default.
>But I'd like to tell exchange to use the qmail box as a relay, and this
>introduces the dilemma.
>
>What if an exchange user needs to send mail to a mailbox local to the qmail
>server? I don't know, but maybe I can tell it "If you don't know this local
>address, relay it to the qmail box."
I'd have to doublecheck my systems, but I think that's the default
behavior of Exchange when told to relay. If it doesn't recognize an SMTP
address, it'll punt it whether it is technically "local" or not. If I'm
wrong on this, I'll correct myself tomorrow when I'm back in the office.
>But then a bad address in the local domain will always start a mail loop
and
>end up in postmaster.
Yes. I'm not sure it would go through as many loops as you'd expect,
but I'd have to doublecheck that too. But I'm not sure I see why that
matters - a bad address is a bounce is a bounce, whether it loops or not.
And since your Exchange servers will be using the Exchange directory for
most local mail users, you'll probably see this very rarely.
In short, I wouldn't lose sleep over this aspect of it.
>I really don't want to split the mail users into subdomains. And I don't
>want to trade email directory info between the two systems (if it has to
>happen, it has to be automatic and immediate ).
>
>So, is this doable with qmail configuration? Has someone done something
>similar?If I have to, I can modify code as needed, but I'd prefer not to
>just to keep things standard here.
With the caveats of the things I want to doublecheck above, you should
be able to do this with a standard configuration. My config suffers a
little from being legacy (we went from an interim qmail+cyrus system to a
qmail -> exchange system).
I'll take a look tomorrow and comment again.
--Greg
