RE: Initial setup enquiry.

  • From: Danny <nocmonkey@xxxxxxxxx>
  • To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
  • Date: Thu, 19 Aug 2004 14:15:40 -0400

On Thu, 19 Aug 2004 18:00:30 +0100, Nick <nick.kirby@xxxxxxxxxx> wrote:
> Hullo, by way of reply, I've tried to map this out in my head and apart from
> a headache, worked out this - please tell me if I am going wrong, and who I
> should contact (for MX records).

Did you go through my steps and did you understand Greg's generous post?

Here is the basic process of me sending an email to nick@xxxxxxxxxxxxx:

I type up an email and click on Send....

My SMTP (mail) server says: Who the heck is As you
know, the goal of a DNS lookup is to find out the IP address of the
server you are trying to retrieve and/or send information to. Well,
lets say you decide to pay to host the DNS for In short, my server needs to find out the IP address of
the server which I can throw SMTP commands and data to so that you get
my email, so it asks (since in this example it is the
authoritative DNS server for for the MX (mail exchange)
record (my goal is still to get the IP address) for, and
responds MX1.WIBBLER.CO.UK with an IP address of (in
THIS example, the routable/public IP address of your firewall/router,
the one you get from your ISP).

(A week later)
Ugh ohh! Your IP address just changed! "Remember, I told you had a
dynamic IP address"

How do a plan ahead for such a disaster (exaggerating here)...

Well, You run a program on your system which tells (your
DNS provider in this example) - "Hey! my IP just changed to, please update my DNS records to reflect the change,
cause my old IP address is useless now".

Anyway, back to the story of my email sent to nick@xxxxxxxxxxxxxxxxx

so, now my mail server has the publicly/routable IP address
( of the server which handles email for
Yaaaa! But wait, a second, your mail server has a private/non-routable
IP address of, how the heck am I suppose to communicate
with it? Well, remember you told your router to forward port 25 (SMTP
traffic) to the IP address of your mail server. Read up on NAT
(network address translation) for more information. Anyway, now my
mail server starts to send SMTP commands and the contents of my email
to your server, which you can view in your inbox.

Hopefully this answers your questions,


Other related posts: