External and
Internet-connected networks
When connecting your mail
server to the Internet (or to another
ex-organizational mailing system that
uses SMTP) you must always make sure
that the rest of the world can
successfully resolve your domain's MX
Record. Failing to do so will cause
e-mail traffic not to be delivered to
you.
In order to properly
configure your domain's MX Record you
should contact your ISP (Internet
Service Provider) or the party
responsible for hosting your DNS Domain
name. They will ask you for your FQDN
(Fully Qualified Domain Name) and IP
address of your mail server. Make sure
you know them.
When
your mail server is
connected directly to the Internet
In cases where no NAT
(Network Address Translation) is being
used and where your mail server is
directly connected to the Internet, you
will need to provide them with the FQDN
and IP address of your mail server.
Note: This is, by
far, the least secure method for
connecting a mail server to the
Internet.
Let's
say you have the following LAN
configuration:
Internet
|
|
|
|
|
192.90.1.1/29 (Real IP from ISP)
|
Internet Router
|
212.143.143.129/25 (Real IP from ISP)
|
|
|
|
|
Mail Server----------------Switching
Hub
212.143.143.130/25
|
(Real IP from ISP)
|
|
|
|
|
|
|
Rest of internal network
In the above example you
need to give the mail server's IP
address as your MX Record.
Domain name: dpetri.net
|
Record FQDN |
Record Type |
Record Value |
MX Pref |
|
mail.dpetri.net |
A |
212.143.143.130 |
|
|
dpetri.net |
MX |
mail.dpetri.net |
10 |
You should make sure the
ISP has had all the necessary routing
tables updated in order to provide
Internet availability to your internal
IP network range.
Note: It doesn't
matter if the real host name of the mail
server is NOT "mail". Internet hosts
don't mind that, they just need to know
what's the name of the mail server, and
what's the IP address for that name. |
