Using POP3 and IMAP4 E-Mail Programs

By default, when POP3 e-mail programs download e-mail messages to your computer, the downloaded messages are removed from the server. Because a copy of each of your e-mail messages isn't kept on the server, you can't access e-mail messages that you've downloaded on more than one computer.

But some POP3 e-mail programs can be set up to keep copies of your messages on the server so you can access the same e-mail messages from more than one computer. POP3 e-mail programs can only be used to download messages from the e-mail server to a single folder (usually the Inbox) on your computer. The POP3 protocol can't synchronize multiple folders on the e-mail server with multiple folders on your computer. POP3 also doesn't support public folder access.

E-mail programs that use IMAP4 are more flexible and generally offer more features than e-mail programs that use POP3. By default, when IMAP4 e-mail programs download e-mail messages to your computer, a copy of downloaded messages remains on the server. Because a copy of your e-mail is kept on the server, you can access the same message from more than one computer. With IMAP4 e-mail, you can access and create multiple e-mail folders on the server. You can then access any message from any folder on the server from computers in multiple locations.

For example, most IMAP4 e-mail programs can be set up to keep a copy of your sent items on the server so that you can view your sent items from a different computer. IMAP4 supports additional features that aren't supported by most POP3 programs. For example, some IMAP4 programs include a feature that lets you view only the headers of your e-mail messages on the server—who the message is from and the subject—and then download only the messages you want to read. IMAP4 also supports public folder access.

POP3 and IMAP4 e-mail programs let you choose when to connect to the server to send and receive e-mail. This section presents some common connectivity options and also provides some factors for you to consider when you select connection options in your POP3 and IMAP4 e-mail program.

Three of the most common connection settings that can be set on a POP3 or IMAP4 e-mail program are as follows:

• Send and receive messages every time that you start the e-mail program   When this setting is used, mail is only sent and received when you start the e-mail program.
  
• Send and receive messages manually   When this setting is used, messages are only sent and received when you click a "send and receive" option in the POP3 or IMAP4 e-mail program.
  
• Send and receive messages every set number of minutes   When this setting is used, your e-mail program connects to the server every set number of minutes to send messages and download any new messages.
  

For information about how to set these settings for the e-mail program you use, see the Help documentation provided with that e-mail program.

If your device or computer that's running a POP3 or IMAP4 e-mail program is always connected to the Internet, you may want to set the e-mail program to send and receive messages every set number of minutes. Connecting to the server frequently helps keep your e-mail program up-to-date with the most current information on the server. But if your device or computer running the POP3 or IMAP4 e-mail program isn't always connected to the Internet (for example, if you connect to the Internet by using a dial-up connection), you may want to configure the e-mail program to send and receive messages manually. Sending and receiving messages manually when you connect using dial-up can potentially reduce the time you're connected to the Internet.

If your e-mail account supports POP3 and IMAP4, you can use many different POP3 and IMAP4 e-mail programs to connect to your account. These programs include Outlook, Windows Mail, Outlook Express, Entourage, and third-party programs such as Mozilla Thunderbird and Eudora. The features supported by each e-mail program vary. For information about the features offered by specific POP3 and IMAP4 e-mail programs, see the documentation included with each program.

Note:
If you don't know if your e-mail account supports POP3 and IMAP4, contact the person who manages your mailbox (sometimes called an e-mail administrator).

The following table lists some POP3 and IMAP4-compliant e-mail programs.

What if I want to know more?

• Access Your Account Using IMAP or POP E-Mail Programs