Managing IMAP Mailboxes With Mozilla Thunderbird

On starting Thunderbird, you should see at least 2 groups of folders on the left of the screen, one of these represents your folders on the central mail server, under the name you gave for your mail account during set-up, and the other group called Local Folders, are those stored on your PC.

Selecting either group of folders will display a list of options in the right pane as below (PC and Mac versions have essentially the same layout):

Clicking and selecting a particular folder will display a list of message headers in the upper right pane and the contents of any selected message in the lower right pane:

This is the Classic view, and can be changed by selecting different options from the View > Layout menu.

You can create new folders by right-clicking on the mailbox you want to create it in (e.g. College IMAP above), then choosing New Folder. You can also create sub-folders by right-clicking on individual folders (except Inbox) and choosing New sub-folder.

Receiving Mail

Unless you have chosen to access your mail via the POP3 method, your mail is stored on the central (IMAP) mail server. When you first log on to your account, new messages will appear in the Message List, in bold text. Thunderbird will check the server for new incoming messages probably every 10 minutes by default. If you need to retrieve new messages immediately from the server, click the Get Mail button.

Organizing Messages In Folders

To create a new folder:

• From the Menu bar, select File > New > Folder. A dialogue box will, requesting the name and location of the folder you are creating.
  In the Name: field, type the name of your folder.
• In the Create as a subfolder of: field, select either the IMAP server folder or a local folder.
• Click OK. The dialogue box will close and your new folder has been added to the sidebar folder list.

What is the difference between the IMAP server and a local folder and which one should you chose? The IMAP server is where your Inbox is located. Local folders are located on your hard drive of your own PC. The benefits of creating a folder on the server include folders being backed up automatically and being accessible remotely through Webmail. The main benefit of creating a local folder on your hard drive is that the content does not count towards your mail quota on the server.

Subscribing To Folders

By default, when you first access your IMAP account, all your folders will be polled for messages and displayed in the folder list. You can change this behaviour by 'unsubscribing' to those folders which you do not need to access regularly.

To see which folders you are subscribed to:

• Choose Subscribe from the File menu
• Check or uncheck the box alongside a folder to subscribe or unsubscribe to it.

IMAP Mail Storage and Quotas

The IMAP service stores mail on the server and this obviously has implications about disk usage. The service uses a quota system that gives each user a limited amount of disk space.  The quota should be more than adequate for most users, but warnings will be sent via email when the amount of mail stored exceeds a percentage of the quota.

To check your quota usage:

• Right-click on any folder in the IMAP folder listing.
• Choose Properties from the resulting menu.
• Click on the Quota tab to display the percent of quota you have used.

To avoid exceeding your disk quota and and having your incoming mail "bounced" back to the sender, make sure that you delete unwanted mail from the server. Deleted mail may either be moved to the Trash folder or just marked for deletion depending on options set under Tools > Account Settings > Server Settings.

Whichever method you use, you should make sure that the Trash folder is emptied or that your Inbox is cleaned up (expunged) when you exit Thunderbird.

Already Over Quota and can't delete?

If you find that you have gone over your quota and can't delete any messages, this is probably because Thunderbird is trying to move the messages into the Trash folder and of course there is no room. If you go into Tools > Account Settings > Server Settings and reset the When I delete a message setting to Mark for deletion, you should then be able to delete and Expunge the messages.

Working Offline (for dial-up connections)

When using IMAP, your mail is stored on the server and you will most likely remain connected to that server while you are reading/composing e-mail. However, it is possible, if you are using a dial-up connection, to work in offline mode, in which case you will work on a local copy of selected folders. When you reconnect to the network, Thunderbird will synchronize any changes you made when offline. You can also synchronize your mailbox manually at any time.

Working offline is different from being disconnected. When you are disconnected, Thunderbird will try to reconnect in order to carry on working. When working offline, Thunderbird knows that you want to remain offline until you choose to work online.

To work offline:

• Choose File > Offline > Download/synch now.
• Check the Mail messages option.
• Check the option to Work offline when download/synch is complete.
• Click on Select.
• Click in the box alongside every folder you wish to work on when offline:

  

• Click OK.
• Click OK again to synch and go Offline.

Once you have the required settings you can switch between working offline and online using the Online/Offline icon in the bottom left corner of the Thunderbird screen:

Using Identities

Thunderbird supports the use of multiple identities for email accounts.

The main features of Multiple Identities are:

• Different settings for different identities. Each identity can have its own sender name and address, reply-to address, signature, vCard and other settings.
  
• When you start a new message, Thunderbird lists all your identities in a drop down menu. You can then select an identity appropriate to the message you are composing.
  
• Intelligent identity detection when replying to or forwarding a message. Thunderbird scans the recipients of the message and chooses the identity that the sender used when sending the message to you. This identity will then be the default identity in the compose window.

Multiple Identities are useful in two common scenarios:

1) For users who have multiple email addresses (aliases) delivered to the same account. For example, you may have a single email account that receives mail for both a role-based address, say com_secretary@qmul.ac.uk and a personal address such as a.person@qmul.ac.uk.

2) For users who read and send mail on and off-campus using the same PC/laptop, when different settings, such as outgoing mail server names, may be required.

For instructions on setting up multiple identities see Using Identities in Thunderbird

Further Help

For more comprehensive help see the Mozilla Thunderbird User Manual (PDF format, IDcheck required from off-campus)