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Your First Day with IMAP

Once you have configured your email client software to use IMAP, you are ready to begin using it. This web page covers some of the practical aspects of using IMAP at Stanford. Consider this information supplemental to the documentation provided with your email client software. In other words, if you have questions about how to do something, you should first consult the client documentation.

If you need more assistance with IMAP, please use the HelpSU system to request it.

Conversion issue: moving mail from POP to IMAP

It is possible that you switched from POP to IMAP with a clean break. Your Inbox was empty, you didn't have any new, unread mail on the mail server, and you don't have any email in local folders (folders stored on your laptop or desktop computer, not on the mail server) that you want to save in your new IMAP environment. Lucky you! You're all set, ready to move to the next topic. But if any of those conditions apply to you, this information may help.

Your @Stanford mailbox on the mail server: Any mail left in your mailbox on the server when you switch from POP to IMAP will be available to you as mail in your IMAP Inbox when you connect to the server. Remember, you have only a single @Stanford mailbox, which you can access with either POP or IMAP.

Mail in your Inbox or other local folders on your own desktop or laptop machine: It is generally easier to move this mail into your IMAP environment as part of the IMAP configuration process. However, if you waited till this point to do it, no harm done in most cases. Here is some advice:

  • If you are using the same email client for IMAP than you used for POP, you will probably see the same local folders displayed in the client whether you use IMAP or POP. In that case, you can simply move/drag the mail from the local folder into your IMAP Inbox (or an IMAP folder; see below). With some email clients you may be able to drag the entire folder; in others, you may have to open the local folder, select all the messages and then drag them; in others, you may be limited to moving messages one at a time. Be aware that you are actually copying, not "moving", the mail from your local computer to the mail server - you probably want to delete the mail from the local folder once the copying operation is complete.

  • If you are using a different email client for IMAP than you used for POP, for instance, if you are using Outlook Express for IMAP but used Eudora for POP, check to see whether there is an import option for importing email (as well as addresses, filters, etc.) into your new client. Usually, this creates a new local folder in your new email client containing the mail from the other. You can then proceed as described in the previous paragraph.

  • If there is not an import option available, you may have to use your old client software, setting it up for IMAP temporarily. Beware, though - if your old software is still configured for POP when you start it, it may download the mail from your @Stanford mailbox and delete it from the server - that's the POP default. But since your@Stanford mailbox is the same as your IMAP Inbox, that means your IMAP Inbox has been emptied. There is no foolproof way to prevent this from happening, especially if your POP client software downloads the mail as soon as it starts up, a typical configuration. The solution, if that does happen, is to go ahead with configuring the old software for IMAP and then making sure the newly downloaded email gets moved back to the server as described in the first paragraph above.

Important: For reasons suggested in the above discussion and also covered in more detail on the web page of IMAP basics, we strongly recommend that you do not use any POP software after converting to IMAP.

IMAP folders and subfolders

A major feature of IMAP is that it allows you to create folders on the mail server where you can store messages in any organizing structure you choose, naming them as you like.

First, a note on terminology. It varies among software client programs. The important thing to understand in IMAP is the basic hierarchical structure of your IMAP mailbox on the server as well as its relationship to your local computer. The following picture, showing the folder structure someone might see using Microsoft's Entourage program, demonstrates this:

folder structure

In this example, the IMAP Mailbox begins near the bottom, at the line INBOX. The IMAP Mailbox is also called your IMAP folder, your @Stanford mailbox, or IMAP Inbox. It refers to the entire collection of email stored on the server for your account. However, it can also mean the specific top-level folder where new mail appears when it is received - in that case, it is most commonly called the IMAP Inbox or INBOX.

The two items below INBOX are subfolders. Most IMAP client programs, such as Outlook Express, make a distinction between subfolders and folders. To them, you can have only a single IMAP folder, the folder called INBOX or, in other words, your IMAP Mailbox. So you may get an error if you try to create a New Folder, since you can have only one IMAP Mailbox. However, you can create subfolders, such as "helpsu tickets" and "IT Services organization" shown above, generally as many as you like. Note that IMAP server subfolders may also be called directories (they are, in fact, UNIX directories) or even (sorry to say) mailboxes.

So, we generally refer to:

  • the IMAP Mailbox when talking about the entire collection of email on the server
  • the IMAP Inbox when discussing the location of newly received and mail waiting to be read, deleted, filed, etc.
  • the subfolder when talking about a folder or directory inside the IMAP mailbox

Local vs. server folders and subfolders

Be aware that you may also have local folders (items such as Inbox, Sent Items and Deleted Items in the example above) — that is, folders that are stored not on the mail server but on your local personal computer instead. You may also create local subfolders, such as the one unimaginatively named "local subfolder" above. Any items you place in these folders are not stored on the mail server, so they are available to you only on the desktop or laptop computer you are currently using.

Local folders and subfolders are not themselves IMAP folders. They are specific to the email client software. For instance, Outlook Express always has a local "Deleted Items" folder, whether you use the program with POP or IMAP; similarly, yet differently, Netscape Messenger creates a local "Trash" folder, again regardless of whether you use it with POP or IMAP. Though used for the same purpose, each folder belongs to its own software. These local folders are not shared between programs (as your IMAP folder is) and cannot be used by other programs. It is likely, in fact, that messages you put into those local folders don't go into a "folder" on your personal computer at all, but are stored within a file created by the client program, and that file is generally unusable by other programs.

In most cases, you can easily move messages around among local and IMAP server subfolders. Be aware, however, that you may be copying, rather than moving, a message if you drag it from a server subfolder to a local subfolder, or vice versa. Dragging a message from one server subfolder to another or from one local subfolder to another will move the message out from one and into the other.

Creating a subfolder

Creating a subfolder on the server is usually an easy procedure — follow the instructions in the documentation provided for the email client you use.

If you receive an error message when you create the new subfolder, try quitting the email program and re-opening it. We often find that the folder was created even when an error message suggests it was not. This is especially likely if the error message mentions a permission problem.

Also, as mentioned above, you may receive an error if you request a New Folder instead of a New Subfolder. Be sure to use the correct command for your email client program.

If the new subfolder doesn't show up in the list of folders and subfolders available to you, make sure you are subscribed to the new subfolder (see below). If you are not, it may not show up.

Subscribing to subfolders

To use a subfolder created in your IMAP mailbox for IMAP mail, you must be subscribed to the subfolder. By default, as part of the process, most email client programs will subscribe you to the subfolder when you create it. However, some, including Outlook Express, do not. As a result, after you create a new IMAP subfolder on the server, it will not show up in the list of active server subfolders, and you will need to subscribe to it to use it.

See the documentation of your email client software for information about subscribing to subfolders.

Deleting email

Most IMAP email clients provide several options for deleting email. For instance, marking a message for deletion may mean that it is purged from the server as soon as you quit the program, or even as soon as you switch to a different subfolder. Or it may mean that the message is moved into a "trash" folder on the server from which you can retrieve the message up till the time the trash is emptied.

Check the documentation for your email client software to see what possibilities are available, and be sure you know how it is configured for you. We would encourage you to use the 'trash method" if accidentally deleting a message from your Inbox could create a major problem for you. Keep in mind that IT Services does not have a backup of a message if you delete it the same day you receive it. For that reason alone, the trash method is strongly recommended.

IMAP storage space

@Stanford mailboxes for non-sponsored SUNet IDs come with a base amount of 5 GB of email storage space or "quota" (faculty receive 20 GB; sponsored SUNet IDs receive 3 GB). When you approach the limit of your quota, you will receive email letting you know. At that point, you should either delete some of your stored mail (you could move it to your personal computer or consider some other storage alternative, such as a zip disk or CD) or request additional quota.

If you need more space, it can be requested through the Sponsorship Manager application. The request must be initiated by someone with Stanford financial authority (SUFIN authority), and the cost of the additional quota is charged to a SUFIN account. More information is available on the Sponsorship Manager website.

Traveling with IMAP

If you are on the road and need to work with your email, the Webmail website ( provides an easy way to check your email.

If you plan to work with your email from a laptop computer while traveling, keep in mind that IMAP is designed for situations where your personal computer can retrieve email from the mail server at any time you request a message. To work well in an "offline" manner, you will need to be certain 1) that all email you need is downloaded onto your personal computer, and 2) that you can re-synchronize the mailboxes when you return.

With IMAP, the master copy of your mail is on the server. Though mail is also downloaded to your personal computer and placed into a local copy of your IMAP server folder structure, it is not necessarily a complete copy at any given time. This is very different from POP. In POP, if you see a summary line for a message in your Inbox, the entire message is there on your personal computer, and you don't have to be connected to the email server to see it. But with IMAP, the summary line may be the only part of the message that has been downloaded to your personal computer. When you ask to see the message, it will be downloaded to your personal computer and then displayed to you, and the copy will remain there on your personal computer till you delete the message in your Inbox. (See "Unexpected" Downloading below.)

So imagine that you decide to take your laptop with you on a vacation where you are far away from a telephone or Internet connection. When you start up your email software, it will show you your Inbox, but it is the local copy of the summary lines for your Inbox, the same way it looked when you ended your previous session. But if you select items from the Inbox that were not previously downloaded, you will not be able to see the messages, since your email program can't get back to the server to retrieve them. For this reason, it is very important, if you plan to travel and want to work "offline", that is, disconnected from the email server, to be sure that all the email you need has actually been downloaded, not just the summary lines. See your email software's documentation for information on how to do this.

Generally, the re-synchronization of the master copy of your Inbox on the email server and your local copy of it works automatically when you connect to the email server the next time. Still, we recommend that you try this out, making sure it works right and you understand how to do it with your email software, prior to any trip where you are counting on it.

And if you do have trouble on the road and can't easily correct it, consider Webmail as a backup.

"Unexpected" downloading

Many IMAP email clients have a pane in their main window that automatically shows the content of any message selected in the folder's list of messages. When that pane is enabled, a copy of the message has been downloaded to your personal computer and will be kept there until you purge the message from the mail server. That is true, in fact, for any message in your IMAP mailbox that you open - to show it to you, the server must first download the message to your personal computer, and it is then kept there until you delete the message. (This is done for efficiency reasons — the message does not have to be retrieved again from the server the next time you examine it. You could think of this as a cached version of your email Inbox.)

One scenario where that could be an issue for you is if you share a personal computer at home with others. If someone else opens your email program, any messages downloaded to your computer could be visible to that person. You may need to consider other security techniques, such as separate logins to the personal computer. (This is an issue for POP users too, of course; however, because the basic principle of POP is that it downloads all your email to your personal computer, POP users tend to be aware of it.)

Last modified August 7, 2014