RE: Initial setup enquiry.

  • From: "Lara, Greg" <GLara@xxxxxxx>
  • To: "'[ExchangeList]'" <exchangelist@xxxxxxxxxxxxx>
  • Date: Thu, 19 Aug 2004 11:00:33 -0400

On the one hand, what you're trying to accomplish doesn't have to be a
terribly difficult exercise - as long as you can grasp the basics and don't
get distracted by unnecessary details. Problem is, there are a lot of
details. I'll describe the fundamental elements of email flow in and out of
a network, and give some pointers on getting your system connected. The hard
work, fleshing out the details and getting it all going, will be up to you.
But that's a great way to learn, isn't it?

When your users send an email to the outside world (joeblow@xxxxxxx), the
server looks at the domain name of the address and sends out a DNS query:
"what is the mail server address for the domain?" If the
folks have done their work well, there will be a DNS entry called an MX
record (mail exchanger) that indicates the IP address(es) of that domain's
mail server(s). The Exchange component responsible for delivering mail to
internet addresses then knows to what server the message should go.

If joeblow@xxxxxxx replies to the message, his server will do the same
thing. It will look up the MX record for (according to your
example), and deliver the message accordingly. Therefore, you must ensure
that there is an MX record for your domain in a public DNS database. This
all assumes that you have a valid domain name registered somewhere
(NetworkSolutions, If you don't, you can usually do this
through the dynamic DNS provider.

[NB: Keep in mind that it's a good idea to not exchange internal DNS
information for a Windows network with the outside world. When thinking
about DNS-related issues, remember that the DNS that runs on your internal
network (server) will be isolated (to a large extent) from the DNS of the
greater internet. Therefore, the DNS records I'm referring to are external,
and must be managed on external systems, whether that's or some
other service.]

Since your network is hiding behind a firewall, you will have to rely on a
firewall feature called port address translation to get incoming mail to
your server. The outside world will only see one IP address - your
firewall's. Your firewall, once configured, will see the incoming email data
(destined, in this case, for port 25) and know that is should be delivered
to your server.

Once your dynamic dns service is up and running, the outside world will know
how to send email to the domain, because there will be a valid MX
record set up. This MX record will point to the IP address of your firewall,
and all email destined for your domain will be delivered there. The firewall
will know what to do with it because you've configured port address
translation to deliver this stuff to your server.

As complicated as that all may sound, that's as simple as I can lay it out,
without leaving large gaps or using too many acronyms and mysterious
catch-phrases. If you feel like you're swimming in too deep water, it would
probably be a good idea to hire a consultant to handle all or part of the
setup. If they're good, it shouldn't take long to get going. In fact, the
whole thing could be done in one day, and within a couple of days the whole
world will know how to reach you.

I hope this helps.

Greg Lara

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-----Original Message-----
From: Nick Kirby [mailto:nick.kirby@xxxxxxxxxx] 
Sent: Thursday, August 19, 2004 4:31 AM
To: [ExchangeList]
Subject: [exchangelist] RE: Initial setup enquiry.

Umm, hokay. I'll be honest and admit that this is a pant browning moment.

I get the non static IPs for the router. No problem there - that I could
probably manage. Probably.

Question does that then equate to an exchange server sending and
receiving email? Sorry chaps, I know everyone is being really helpful, but
you're olympians and I'm more of a family bike ride.

Assuming I have No-IP set up, and NOIP knows where I am, and my internal
network is using say as my domain name, and my exchange server
is sending mail for (internally), who gets the DNS information?

getting stuff out is relatively easy, as once a packet is forwarded to the
"outside" then it's out, but people knowing where to get back in worries
me. Does the FQDN then have to be public?

Start again - if I use my public FQDN for my internal network of ten or so
machines, yet put those on private addresses (192.X) will I still be able
to send and receive email using SMTP, and, crucially allow other people to
send me email to the public email address (which, in theory it would be as
it'd be globally visible yet hidden).

I do a lot of thinking aloud.Sorry. All thoughts gratefully received.



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