Different email systems explained

Note: this article dates from 2005, and is being preserved for posterity. While my own email systems have now changed to IMAP—and I recommend IMAP for everyone wanting to access email from his computer and other devices—the main points about the various email options outlined here still stand.

There was a time when the tech-related question I was being continually asked was about the different options there are when it comes to email services. Several years later, I’ve now decided to write this article so that the next time someone asks me the same question, I can say, ‘look at my website!’ So, what follows is a beginner’s guide to the different types of email service available and my efforts at explaining the pros and cons of each of the four major technologies—Web-based email, POP3, IMAP, and email managed by a Microsoft Exchange server.

1. Web-based email

This is often people’s first foray into the wild world of email: for many people, the word “Hotmail”—possibly the most popular Web-based email service, bought many years ago by the Microsoft Network—is synonymous with email. You sign up to a service (most likely free) and you get an email address for that service, together with a certain amount of storage space for your email. You access the email by signing in on the service’s website.


  • All of your email is stored on another computer, so you can access your email over the Web all over the world, which is an obvious bonus.
  • You don't have to worry about faffing around with server settings on your computer—as long as you can use a website, you can use your email.


  • You must be connected to the Internet to be able to read your email.
  • You might one day outgrow the amount of disk space available to you to store your email (especially if you’re a hoarder, like me) so you’ll have to delete some before the service allows you to receive more, although many services are now following Google’s lead with its Gmail service, which has a massive 2GB free disk space for each user.
  • If your Internet connection is slow, then trying to find old messages can be a painful experience as you load page after page looking for the message you want.

There are some definite benefits to Web-based email, especially if you’re going to be travelling and using different computers, but there can often be a Web-based component to other, more flexible, email systems, as I’ll describe below.

2. Email delivered over POP3

Right, POP3 stands for ‘Post Office Protocol, version 3’. I’m not going to explain in detail what this means, but in brief, email is passed from the server of whichever email service to which you subscribe to some application on your own computer (I’ll come on to suggest a few such applications in a moment), where it is then stored. The commands issued by the application on your computer and the responses given by the server conform to a pre-defined language, or ‘protocol’. Having a standardized protocol like this is very beneficial, because it means that anyone could write an application which would be compatible with all of the millions of POP3 servers all over the world.

Applications that you might have seen on your computer which can access email by POP3 include Microsoft Outlook, Microsoft Outlook Express, Mozilla Thunderbird (cue mentions of International Rescue, etc.), or Apple’s ‘Mail’. These all connect to a mail server as I described above, see if there are any new messages, and if there are, they begin to download them onto your hard disk. Once downloaded, the application wipes them off the server because you’ve now ‘got’ them, and so that they no longer take up the precious disk space assigned to your account. Most POP3 applications have got a setting not to delete messages from the server, but if you choose this then your server will likely fill up quickly and start refusing incoming email.


  • Your email is on your computer, so you can browse through it with impunity, and without needing to be connected to the Internet. The only limitation of space is the size of your computer’s hard drive.
  • An application on your own computer behaves quicker than any website can, and most POP3 applications can perform searches of your email far more accurately than Web-based services.
  • The address book functions on your computer can be far more effective than Web-based services, not least because they are faster to access, fuller, and can often be set easily to synchronize with devices like palmtop computers (PDAs) and mobile phones.


  • Once email is downloaded, you can only get to it from your own computer.
  • If your computer dies, and you haven’t followed all the advice to backup, you’ve lost all your old email.
  • POP3 email services are often offered by ISPs when you open an account with them. They also often have a Web-based component, so that you can view messages that haven’t been downloaded onto your computer (and thus deleted from the server) on a website. This is very good for when you are travelling—you can get your email from any Internet café in the world, and it is safely downloaded onto your computer when you get back home. The only problem that can arise is that messages that you send via the website (rather than from your POP3 application, which incidentally uses another protocol—SMTP—when sending messages; are you confused yet?) aren’t automatically saved into your computer’s ‘Sent Items’ folder.

3. Email delivered by IMAP

Hmm, I’ve always found this a slightly funny one. Another protocol—IMAP (Internet Message Access Protocol)—is less commonly used than POP3. Again, you use an application on your computer to communicate to the server which stores your email. Most POP3 email applications also support IMAP. You could say that IMAP is like a combination of POP3 and Web-based email, because your email is primarily retained on the server of whichever service you use, but rather than accessing it over the Web you use a dedicated email application, which keeps a local ‘cache’ copy of your email, so that you can use your email whether or not your computer is still connected to the Internet. It’s very useful, if you’re using a laptop, to be able to access your email while on the move so that you can prepare replies and read longer messages at leisure which you weren’t necessarily able to peruse while online.


  • Your email is stored on the server, with a copy of the email synchronized onto your computer. This affords you the best of both ‘worlds’ in that you can get to your email even when offline, but you can also access your email from all over the world—IMAP services often come with a Web-based component, or if you have more than one computer you could set up applications on each one to use the same IMAP account so that you can get to all your email from any of your computers.
  • You can sort your email into folders, and these folders are in turn stored on the server.
  • Same comments about address books on your computer as for POP3 email services, above.


  • In practice, I’ve always found IMAP to be somewhat clunky. It doesn’t behave as I’d expect—for example, if you delete an email, it only crosses it out on the list (rather than, say, being moved to a ‘Deleted Items’ folder)—you can only get rid of it by subsequently choosing to ‘purge’ items that you’ve marked for deletion.
  • The process of synchronization of email can be somewhat slow. Also, it is only received email that gets synchronized—email that you write stays only on the computer you wrote it on, and isn’t synced onto the server.

4. Email managed by a Microsoft Exchange server

Now, this is quite advanced stuff—this is how I've now got my email managed. An account on a Microsoft Exchange server can work out to be quite expensive —not least because it can be pretty expensive for a company to set up a shared Exchange server (in comparison to, say, POP3 or IMAP servers, where you can get accounts for nothing), but also because Exchange server still isn’t that widely known in the consumer email marketplace.

Microsoft developed—and still develops—its Exchange server software for fairly large organizations. Rather than just handling email, it does everything that the desktop application Microsoft Outlook does. Indeed, Exchange server has been designed as a complement to Outlook—it deals with email, calendar, contacts, notes, and addresses, as well as providing other services to slot into the Outlook that you might already know. For example, colleagues within an organization can share details about their upcoming schedules over the server, so that if you are arranging a meeting, you can carefully fit it around all the other things occupying the time of those due to come.

This is all very well, I hear you say, but what can some pretty obscure Microsoft product designed for corporations do for me and my email? Well, I’ve found that the Exchange server system has done for me what I always thought that IMAP would do and at which IMAP failed miserably in my experience. Everything—email, contact details, calendar, and the other things—is primarily stored on the server. I’ve set up Microsoft Outlook on my Windows XP PC to connect to that server and synchronize with it—so everything has a local copy on my computer. If I change things on my computer, it updates the server accordingly. The beauty of the system really comes into play because I also use an Apple PowerBook—I’ve set up Microsoft Entourage (the PIM application provided as part of Microsoft Office for the Mac) to synchronize with the Exchange server too, so another copy of everything is also kept on my PowerBook for when I’m travelling. I write and send an email from the PowerBook, and it appears even in the ‘Sent Items’ folder in Outlook on my Windows PC. I move an email I’ve received from one folder to another, and it appears in that folder on any computer I use to connect to the server. It’s all pretty useful stuff, and once set-up it’s a total breeze to use (all you need to know is how to use Outlook on the Windows PC, or Entourage on the Mac). There are non-Microsoft applications which claim to be able to work with Exchange servers, too: I tried using Apple’s Mail application (provided with OS X) and found it was rather flaky, and didn’t support the full set of features that I could get to with Entourage. Admittedly, I find it rather annoying that Entourage can’t do some of the quite advanced stuff that I’ve been doing in Outlook (extensively customizing views, for example), but it does have extensive support for most of the ‘normal’ functions.

Oh, if any member of my family wants to get onto the Exchange server account I’ve set up with 1&1 Internet (so far it’s only my parents and me who are using it), then that’s perfectly possible if you get in touch with me. It'll set you back about £70 GBP per year: you can either carry on using your current email address (if you set it up to forward to the server, which is pretty easy to do) or you can get a new email address under the new family domain name. This is no longer quite true, but I can still arrange email service for family-members on an Exchange server or (now more preferably) an IMAP server.


  • Your email (even sent messages), contacts and calendar information are all stored on the server, with copies synchronized onto your computer.
  • You can easily use multiple computers to access the same account and have full access to all email, contacts, and calendar information, regardless of which computer you originally used to read the email or save the contacts or calendar appointments.
  • All your email sorting is preserved in the folder structure of the server.
  • There is a very extensive Web-based interface for Microsoft Exchange servers—if you are using the Internet Explorer Web-browser on Windows computers, using the Web access to everything on the server is almost exactly like using the full-blown Outlook application. In other browsers and on other operating systems you have to put up with a rather more basic interface, but even so you still have access to all your stuff from any Web-connected computer in the world.
  • Same comments about address books on your computer as for POP3 and IMAP email services, above.


  • Of all the methods listed here, this is the most expensive way of managing your email.
  • There are relatively fewer services which provide Exchange server accounts for consumers (strictly these are called ‘hosted Exchange’) than for the other types of email service I’ve discussed here.
  • As with Web-based email and the IMAP system, you are limited by the amount of space available to you on the server. The account I’ve been using has 1GB of space for each user, which is more than ample for my needs.

One Comment

W. E. Hence

9 January 2009, 12.31 pm 

Thank you for such a well-written and concise explanation of these options.

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