Internet Mail

There are two ways of distributing Internet mail in a small network. One is to use its own dedicated mail server, the other is to use an external (ISP’s) mail server. The latter (shown below) is by far more popular.

Dedicated mail server is typically installed on the gateway host where it does not require a separate mail proxy. However, the mail server setup is quite complex. Its configuration is not trivial. The mail server usually requires a host running 24-hour a day and a permanent connection to the Internet. These requirements are not practical for many small networks (e.g. those with dial-up access to ISP.) That is why a dedicated mail server is rarely seen in very small networks of two to ten computers. However, as the network size grows, the performance and utility of a dedicated mail server begin to outweigh its disadvantages.

Utilizing the ISP’s mail server to distribute Internet mail to/from a small network is convenient, simple, and thus a very common solution. In order for a mail client on an internal computer to connect to the ISP’s mail server, a mail proxy must be installed on the gateway.