How to configure the infrastructure required to host a mail server


Many home users and small companies use an ISP for hosting mail infrastructure, and in-source their mail server. To effectively host a mail server, ensure that a permanent connection to the Internet is available. This article describes how companies can migrate messaging infrastructure into their organisation.



The first step in publishing a mail server is to configure a Microsoft Windows server that can be accessed from the Internet. There are a variety ways to connect the server to the Internet, the common ones are outlined below:

Dual Network Card Configuration
The simplest approach is to ensure the server has two network cards. One of these cards should be configured with the IP Addressing scheme of the Internal network. The other network card should be configured to access the Internet using the settings supplied by your ISP. On this server, either run a Proxy Server or enable Internet Connection Sharing (if using Windows 2000). This will provide a basic firewall between the internal network and the Internet.

Cable Router Configuration
Many home users and small companies use a Cable, DSL or ISDN router/hub to provide Ethernet access to the Internet. This provides the same functionality as the option outlined above, except the hardware, software and maintenance costs are reduced. These devices cost around $150 (USD). Such devices provide Address Translation and can therefore function as a Proxy Server. Since these devices only expose an external IP Address, the Network/Port Translation on the device will need to be configured to allow Internet traffic on ports 110, 25, 80 and 8080 to translate to the internal address of the mail/web server.

Enterprise Configuration
Larger companies often interface to the Internet through a router of some description. This router provides Ethernet access to the Internet (the router is normally supplied and configured by your ISP). Most routers have an inbuilt Ethernet switch that will allow the server to be placed on the Internet (assuming that an appropriate public IP Address has been configured for the server). The simplest approach in this situation is to place the mail server directly onto the Internet and use an alternate interface to provide connectivity to the private network. In many cases, companies use a firewall with multiple translated interfaces to provide what is called a DMZ (Demilitarized Zone). For more information about configuring servers within a DMZ, consult the documentation supplied with this device.


By now, the mail server should be accessible through the Internet as well as internally. The next thing to do is configure the DNS settings. In order for other mail servers and clients to be able to send mail to your mail server, the appropriate published DNS records are required. These records are used by other mail servers to locate your server when they attempt to parse recipient addresses (i.e. the records allow a domain name to equate to an IP Address). Exactly how DNS is configured depends largely on whether you are hosting your own publicly accessible DNS server or whether a third party (typically an ISP) is hosting your DNS for you.

Traditional DNS implementations require a fixed or static IP address allocated to the public interface of the appliance (router/server) that is the first point of connection to the Internet. If the server has a static IP address, it is possible to register an MX and associated DNS record that resolves to the external IP address of the router/server. If  the server does not have a static IP Address, the domain will have to be registered with an ISP that provides Dynamic DNS services. Dynamic DNS works by having an agent installed on the public router/server interface that effectively notifies the DNS Service provider of the IP Address. Most Internet Firewall Routers have this capability built into their firmware. For more information on configuring Dynamic DNS please refer to the documentation supplied by the DNS Service provider or with the router.


Having configured both Internet connectivity and publishing DNS settings to the Internet. All that remains is to install the MailEnable server software. To do this, download the installation kit and run the installation wizard. The installation wizard prompts for the IP addresses of the DNS provider. Use the settings published by your ISP (or if you are hosting your own public DNS, use the local server's IP address). Once installed, run the MailEnable Diagnostic Utility to ensure that the configuration is correct.


Please refer to the MailEnable Quick Start Guide for further instructions:

Which DNS should be used with MailEnable?: Article ME020043

How do other mail servers locate my newly installed mail server? Article ME020019

What DNS Records be created when hosting mail domains?: Article ME020048

Product:MailEnable (All Versions)
Class:HOWTO: Product Instructions
Created:17/09/2002 1:18:00 AM
Revised:Friday, February 22, 2019