Messaging Server

Say what you want about the Web, but over the past decade the biggest Internet-driven engine for business change has been e-mail. Once a niche application that ran only on internal company networks, global standardisation on the TCP/IP suite of communications standards has made Internet e-mail the easiest, fastest way of communicating with anyone, anywhere.

If you're online, you're probably using e-mail; surveys regularly show it's by far the most commonly used Internet service. The benefits, particularly for a small business, are immense: instant communications with partners, suppliers and customers; asynchronous communications, meaning you can still get an order without having to sit by the phone; a clear audit trail so you know who said what, when; and a seamless way to market your business to the world.

Although it's crucial for today's business, e-mail remains a black art for most: push the send button, wait a few minutes, and your message pops up at your partner or customer. They write back, and you have your answer.

By understanding how e-mail works and how it folds into the broader capabilities of today's messaging and collaboration platforms, it's possible to use it for much more than just writing people. Intelligent use of attachments, online collaboration, scheduling of meetings, exchange of contact details – e-mail is a powerful tool that can help expand your business in new ways.

E-mail in a nutshell

So what, exactly, does happen when you press the send button?

First of all, your e-mail program (for example, Microsoft Outlook Express, QUALCOMM Eudora, Netscape Mail, Lotus Notes, Unix's PINE or Cyrusoft Mulberry) connects to a server running SMTP (Simple Mail Transport Protocol), a standard that defines how e-mail is addressed and sent. This server might be located in your office or at your ISP; we'll explain the difference later.

Every e-mail sent over the Internet has an SMTP header – a series of lines that are prepended to the beginning of your message, but don't usually show up when you're reading messages. These lines are like an address on an envelope, and contain information such as the name and e-mail address of the sender and recipient; the name of any attached files; the e-mail's subject; and a list of the various servers that have handed off the message on its way from sender to recipient.

SMTP headers also list details of any files attached to the message, including both their filename and a MIME (Multipurpose Internet Mail Extensions) code describing what application can be used to load the file. MIME also specifies how e-mail programs attach files through a process called 'encoding'.

Encoding is necessary since files on disk are represented with 8 bits – the numbers from 0 to 255 – but TCP/IP e-mail systems only transmit using 7 bits -- 127 text characters, including uppercase and lowercase letters A through Z, punctuation, numbers and some special symbols. That means it takes eight text characters to represent seven characters in the original file, and that an e-mail with a 700KB attachment will actually be 800KB in size. Once the message is received, it's converted back into 8 bits and opened or saved onto disk.

Your e-mail client automatically attaches a SMTP header to every e-mail you send. Once that message is received by the SMTP server, it splits the recipient's e-mail address into a user name (the part before the @) and an e-mail domain (the part after the @). If there's no domain, the SMTP server assumes you've written someone in the same company and sends it straight to your company's message store (a dedicated database, like a post office box, where all incoming e-mail is stored until you go to pick it up).

Otherwise, the SMTP server checks with a DNS server – a directory of Internet domain names that may be hosted in your office or by your ISP – to get the IP address of the recipient's SMTP server. This address is inserted into the SMTP header, and the whole message is shuttled onto the Internet to find its way to its destination.

Once it gets there, the same process happens in reverse: the SMTP server checks the recipient's name and consults its records to make sure the address is valid. If it's not, the SMTP server bounces the message back to the sender.


Recipients can retrieve their e-mails using an e-mail client that supports POP3 (Post Office Protocol 3) – all do -- which checks the message store to see what's new. Mail can be retrieved using any device supporting POP3, which these days includes a desktop, notebook, PDA, many Web mail accounts and even some mobile phones.

On its own, however, POP3 has one major deficiency: it doesn't let you preview your messages before downloading them. This means that if you commit to retrieving messages and you've received a massive attachment, you may be waiting for minutes or hours before you can read your e-mail. If you're travelling and dialling in using a modem, that costs a lot.

To fix this problem, many e-mail clients also support IMAP (Internet Message Access Protocol), which lets you initially download just header information, then download the e-mails you choose with or without attachments. This gives you much better control over messages and can save you considerable time and money.

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PC World Staff

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