Because it’s easy, and usually free, most home and small-business users rely on the hosted email server facilities offered by their Internet service provider (ISP) to send and receive messages.

However, if you have your own network there’s no reason you shouldn’t run a mail server of your own, with numerous benefits.

A server of your own lets you send messages over the local network without having to connect to the Internet.

It also provides total control over user mailboxes with no artificial limits when it comes to message size or attachments, and a free rein in terms of anti-virus and spam protection, content filtering, message archiving and so on.

Plus you can implement your own calendar and address book sharing and other collaboration features, over and above basic messaging services.

A locally hosted mail server makes it easier to switch service provider, which can be a real boon for the growing company and needn’t be costly or difficult to run.

But careful planning is still required, with decisions to make in terms of what to buy and how it’s put together, which is what this column is all about.

Server requirements
One of the first things you’ll need is a proper email server package and suitable hardware on which to run it. Contrary to what some vendors might tell you, there’s not a huge amount of processing involved and you don’t need a powerful or dedicated system.

On a small network, an existing file or web server will usually be more than adequate or, failing that, a spare PC that can be left switched on all the time. Just make sure the system has plenty of memory and enough disk space for all the messages you expect to handle.

Neither do you need an expensive server operating system. A lot of the small-business mail server packages can be run on ordinary desktop versions of Windows, while most Linux users will find suitable open-source mail server software bundled as standard.

Which client?
You’ll need a client for users to connect to the server, but that too is pretty easy to sort out.

Chances are you’re already using Outlook or Outlook Express to connect to your ISP’s mail server and there’s no reason you shouldn’t do the same when deploying a server of your own.

Alternatively, there are plenty of other email clients, including Eudora and Thunderbird, the free email client from Mozilla, the company behind the open-source Firefox browser.

Some mail packages come with their own client software, and browser-based webmail clients are increasingly supported.You will need to decide what protocols to use when connecting clients to the server.

Not so much for sending mail, where the Simple Message Transfer Protocol (SMTP) is more or less universally employed, but in terms of how messages are retrieved, with a choice between Pop3 (Pop is short for Post Office Protocol) and Imap (Internet Mail Access Protocol).

As with SMTP, these protocols are almost universally supported by both servers and clients, but they work in quite different ways.

With Pop3, users download their email messages to their local PC before opening them, whereas with Imap the messages stay on the mail server and only brief summary (header) information is ever downloaded.

One of the benefits of Imap is that it allows users to access messages from any PC, not just their own. They can also be given easy access to their mail remotely, using a secure VPN tunnel to the server, for example. Imap is also widely used to provide collaboration features such as shared address books and calendars.

However, server-side support for Imap can vary, and it’s not quite as robust or well defined a standard as Pop3. Plus, if you want to keep messages on the server and provide easy remote access, web-based clients are arguably better and more flexible.

Developers are increasingly ditching Imap in favour of other ways of implementing collaboration features so take care before choosing an Imap solution.