Since the server is able to operate in several modes it is highly recommended that before its actual installation and primary set up you decide how exactly it will be used. You can obtain some of the technical data (the IP-address of the DNS, provider's mail server settings) by contacting your ISP.

The mail servers widely use the Domain Name System (DNS) for delivering e-mail messages. The DNS allows the server to decide which mail server is responsible for receiving e-mails for a specific domain (using the MX records). Usually there are several servers and each of them has its own priority. Such method makes it possible to considerably increase the reliability of the mail subsystem on the whole, because if a certain server is temporarily unavailable another one can successfully replace it. For even better flexibility in the MX entries instead of the IP-addresses of the mail servers the names of their hosts are used. In order to determine the IP-address by the host names the DNS is used too (the A records).

First of all you have to decide whether the computer on which you plan to install the server will be permanently connected to the internet or will go on-line periodically. This issue is very important since the DNS access often requires permanent connection to the Internet. Sometimes the server has no connection to the Internet, but nevertheless has access to DNS. It is possible if the server is used exclusively for internal needs in the local network, e.g. in order to organize the file exchange within a company. However, in this case there is no need in the DNS access as all operations are carried out within a single server.

Therefore the server can be set up in three different ways:

The BatPost mail server is flexible enough to be set up in these three different ways and successfully manage the e-mails. All you need is to change several server settings. Our next step is to have a closer look at each of the three ways of setting up the server and providing you with some recommendations.

Permanently on-line

If the connection to Internet is permanent it is preferable that the server distributes the e-mail on its own using the DNS. In this case you have to find out the IP-address of the DNS server. Such data can be provided by your system administrator or your ISP. However, in case of the self-reliant delivery it might be necessary to create your own mail domain, because some servers perform extensive verification and refuse to receive mail from servers not registered in the DNS. If you do not intend to register your own domain then you can distribute mail via the provider's server or via any other relay server.

Periodically going on-line

If the server connects to Internet for short periods of time then the usage of DNS and direct mail distribution becomes ineffective. In this case it is more convenient to use the provider's server both for receiving the incoming mail and sending the outgoing messages.

For retrieving the incoming mail either the Remote POP (RPOP) or ETRN/ATRN technologies can be used. In the first case BatPost will connect to  the external server via the POP3 protocol and fetch messages. Then it will analyze the messages' headers to determine their recipients. In the second case the special ETRN/ATRN protocol will be used in order to get messages from the external server's sending queue. The latter one is preferred to the first one, because in that case the message recipients are unambiguously identified, though it is mandatory the external server is specially set up which is not always possible.

For sending the outgoing mail the ISP's server will be used as the relay server.

Configuring the server that way is more difficult as there are many settings that have to be taken into account. Anyway, you will have to discuss all the details with your provider and receive all the necessary information on the settings.

No connection to Internet

If there is no connection to Internet at all then the internal DNS can be used. It will allow having several mail servers in the local network. Note that the DNS records are local network specific and are of no practical use outside it. In most cases the DNS is also absent and all the operations with messages are performed within one mail server. In this case, though in reality messages will not be distributed at all, you have to define the relay server as the method of distributing the messages. Relay server settings in this case are inessential.

Server installation

As soon as you decide the way the server will be functioning and as soon as you have all the necessary information on the settings, you can proceed to the installation of the server. Here are the steps you will go through installing BatPost:

In case the server will periodically go on-line check the advanced settings.

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