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Understanding POP, IMAP, Exchange, and Webmail

When you set up an email account, you’re likely to see a confusing choice of protocols. There are four main ways to receive email on your computer. One of them — webmail — is obviously different and relatively easy to understand. The other three — POP, IMAP, and MAPI (Exchange) — require a bit more explaining. Here’s a quick overview of what they’re all about, without getting too deep into technical details.

The reason it’s so chaotic is that email is one of the oldest functions of the Internet, preceding the Web by many years. In those days, people set up something that worked, without any notion that someday the whole world would be using it.


The oldest of the protocols, POP, dates back to 1984. The name stands for “Post Office Protocol,” and the current version is POP3. It’s designed to access the mail server and download all messages, after which they can be deleted from the server.

IMAP, first seen in 1986, stands for “Internet Message Access Protocol.” It assumes that mail resides on the server and downloads it only as it’s needed. Even when you read it on your mail app, you may have just a temporary copy unless you explicitly save it. IMAP lets users access their mail from several different machines, but previously read mail might not be available when they don’t have an Internet connection.

These two are the main choices for non-Microsoft, non-Web mail. POP is more attractive if you like having all your mail archived on your own computer. You can set it up so that mail is deleted only when your main computer reads it; that way, you can read it first on a mobile device and still know that you’ll get it on your desktop computer when you check mail later.

POP and IMAP are just for receiving mail. If you use either of them, you’ll use a different protocol, SMTP (Simple Mail Transfer Protocol), for sending mail. Your mail client should automatically set this up for you, but you should look at your provider’s instructions for anything unusual about the setup.

MAPI (Microsoft Exchange)

MAPI, the Messaging Application Programming Interface, is what Microsoft Exchange uses. It’s more complex than POP and IMAP, and it’s generally used with Microsoft Exchange Server. MAPI supports not just email, but calendar synchronization and other services.

There’s a widespread myth that with Exchange Server, you have to use Outlook or some other MAPI-compatible client. Exchange Server also supports POP and IMAP clients, though people who use them can’t take advantage of the non-email features.

Which should you use?

If you’re using Microsoft Exchange Server and Outlook, it’s practically a given that you’ll use MAPI. It’s what Microsoft designed the software for, and it gives you the broadest capabilities. If your mail server is Exchange, but you aren’t using Windows or don’t want to use Outlook, there are many compatible client applications for all platforms.

If you use a mail application with a non-Microsoft server, your choices are POP or IMAP. IMAP is more popular because a lot of people check mail from multiple devices, but the choice is a matter of taste. If you prefer having all your mail on your computer rather than on the server, POP is fine.

Whether you use POP, IMAP, or MAPI, it’s very important to configure it for a secure connection. With POP and IMAP clients, you may see this described as an “SSL/TLS” connection. Outlook simply calls it an encrypted connection. Some mail servers don’t include a secure option; it’s risky to use them, but sometimes you have no choice. Just be sure not to use non-secure email over non-secure (public) Wi-Fi; that’s extremely dangerous.

The reason you need a secure connection isn’t so much to hide your messages as to keep your passwords from being intercepted. With the non-secure protocols, you’re sending your password as clear text. If you send it over public Wi-Fi, then anyone can listen in on your session and get your username and password.

What about webmail?

Webmail is a perfectly good alternative to these protocols, it’s simpler to set up, and it can offer better security. You can access it from anywhere you can run a Web browser. You can view attachments such as PDF files in your browser, which can be more convenient than downloading them.

The main drawback is that your mail is all on the server, and it’s generally less convenient to save a local copy from webmail than it is from an IMAP client. If you lose your account, you lose any mail you haven’t downloaded.

All four choices for email can be good under the right circumstances. Hopefully this guide will let you feel less overwhelmed about finding the best configuration for your email.

In the end, you just want it to work, and that’s what BWS delivers. To learn how we can bring you the best solutions for all your IT issues, please contact us.

  • 09/23/2016
  • IT