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Thunderbird at Sussex for Staff and PhD students

NOTE: This Guide is for STAFF and PhD students, whose email is hosted on the Exchange system at Sussex. 

Thunderbird is a product of the Mozilla organisation and is a stablemate of the popular Firefox web browser. It is popular as an email client, being powerful and easy to use.

This Guide applies to Thunderbird version 17.0 and above.   Earlier versions may differ in the procedures described below.

Please note that Thunderbird is not formally supported by IT Services and we would recommend that you use Outlook as an email client. However, the following information will help get you started if you do choose to use Thunderbird. 

Installation instructions for Thunderbird can be found on the Mozilla Thunderbird website.


  1. Installing your first Thunderbird account
  2. Installing extra Thunderbird accounts
  3. Optional Settings
  4. Finding out more about Thunderbird

Installing your first Thunderbird account

If you have just installed Thunderbird for the first time on your computer, it should offer an account set-up dialogue immediately after starting.  Set up an account with your Sussex settings by following the steps below.  If you have already installed and used Thunderbird and want to set up a new account, see the section Installing extra Thunderbird accounts below.

  1. If you see a System Integration dialogue box, click the Cancel button to close it:

    T'bird System Integration dialogue

  2. You should then see a Welcome window with the question, Would you like a new email address?
    Click the Skip this and use my existing email option button at the bottom left.

  3. In the Mail Account Setup dialogue box, enter your real name, your Sussex email address and your password in the boxes provided.  De-select the Remember Password box so that it is unticked. Then click Continue:

    New account - step 1

  4. Thunderbird then attempts to set your server and account settings for itself.  You will need to change the settings, so click the Manual config button (note: the position of the button may differ from that shown below):

    New account - step 2

  5. The server settings should be as follows:
    Incoming: IMAP, server hostname, Port 993, SSL should be SSL/TLS and Authentication Normal password.
    Outgoing: (SMTP), server hostname, Port 587, SSL should be STARTTLS and Authentication Normal password.
    Ensure only your username (for example, ano23) is shown in the Username box.
    Finally, click the Re-test button:

    T'Bird manual account configuration

  6. You may notice that some of the settings in the boxes have changed, so change them back to what they were, as shown below. Finally, click the Done button to install this account and its settings into Thunderbird (DO NOT click the Re-test button).

    T'Bird manual account configuration - reset settings
  7. If you're using Thunderbird on your staff PC, it's important to change the local folder where Thunderbird stores messages on your computer. By default, Thunderbird saves data in your Windows roaming profile which will slow down your logins on campus computers:

    • Click on Advanced Config
    • Click on Local Folders on the left-hand side and then, in the Local directory section, click Browse
    • right-click on your N: drive in the left-hand nav pane and choose New and then Folder
    • call the new folder Thunderbird, click to highlight it and then click Select Folder
    • click OK and restart Thunderbird if requested to do so

Installing extra Thunderbird accounts

To add another account, click on Thunderbird's Application menu button as shown below, then click Options... and then Account Settings...:

T'bird applications menu

Then, click on the Account Actions button at bottom left, and click on Add Mail Account... as shown below:

T'bird account actions button

Then simply follow steps 3 onwards in the section above to create another account.

Optional Settings

Default email client setting

As standard, when installed, Thunderbird will set itself as your default email client.  That means that when you click on a weblink to email someone, Thunderbird will be used.   If you prefer not to have Thunderbird as your default email client (for example, you might use it only to access certain email accounts and you might normally use Outlook for your work email), you can undo the setting like this:

  1. Open Thunderbird's Tools menu and choose Options.
  2. Click on the Advanced tab.
  3. In the System Integration panel, untick the Always check... box, then click the Check Now button.
  4. Untick the E-Mail option in the list of options, then untick the Always perform this check... box.
  5. Click OK.

Folder views

As standard, Thunderbird will show only the folders you have subscribed, usually in another email application.  It's usually more convenient to view all your folders, whether you have subscribed them or not.  To view all folders, follow these steps:

  1. Open Thunderbird's Tools menu and choose Account Settings.
  2. Click on Server Settings from the column on the left, under the account for which you want to set the folder view.
  3. Click the Advanced... button at the lower right corner of the Server Settings panel.
  4. In the Advanced Account Settings window, ensure the Show only subscribed folders box is unticked, and the two boxes below it are ticked (see below).  Then click OK.

Deleting messages

We strongly recommend that you delete messages you no longer need.   This will help you manage your mail more effectively and also helps to preserve storage space on the server.  The following settings will make message removal a more automatic process.

  1. Open Thunderbird's Tools menu and choose Account Settings.
  2. Click on Server Settings from the column on the left, under the account for which you want to set message removal options.
  3. In the Server Settings panel, we recommend that you select Just mark it as deleted under the When I delete a message: heading, and click to select the Clean up ("Expunge") Inbox on Exit box.   Both settings are shown in the image below.
  4. Click OK to save these settings.

Adding a signature

To set up a signature to add to your outgoing emails, follow these steps:

  1. Open Thunderbird's Tools menu and select Account Settings.
  2. Click on the required account name in the list on the left to open its Account settings window.
  3. Enter your signature text in the Signature text window.  

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Attachment handling

Thunderbird can sometimes give problems opening attachments - it may report them as damaged or corrupt, even if they are known to be undamaged.  This is usually caused by the server reporting the wrong size for the attachment.

Adding '' automatically to addresses in draft messages

To add the sussex domain to an address as you are typing, open the Tools menu, choose Options, then Advanced and then General and click on Config Editor. Then scroll down the long list to the line containing mail.identity.default.autocompleteToMyDomain
Double click on this line so that the value changes to TRUE, then close the editor window by clicking its X button.   Then click OK.

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Creating and deleting mail folders

To create a new folder, right-click on your account name in the column on the left, OR right-click on an existing folder if you want to create a sub-folder in the selected folder. Then choose New Folder or New Subfolder as appropriate from the drop-down menu, and enter the name of the new folder. Use only alpha-numeric characters (letters, numbers and hyphens) in the name.

To delete a mail folder, simply right-click on the folder name and choose Delete from the drop-down menu.

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Setting up access to the LDAP address book

    1. Open Thunderbird's Tools menu, select Options, then Composition, then Addressing.
    2. Click both Local Addressbooks and Directory Server to select them.
    3. Click Edit Directories and then click Add.
    4. In the Name: box, enter Sussex OpenLDAP
    5. In the Hostname: box, enter

    6. In the Base DN: box, enter

      ou=staffaddressbook,o=University of Sussex

      (you must enter this exactly as shown, or use copy & paste)

    7. In the Port: box, enter the number 636 (replacing anything already there)
    8. In the Bind DN box, enter

      uid=username,ou=unix,ou=uscs,o=University of Sussex

      (where username is your own username, for example ano23 - otherwise enter the text exactly as shown, or use copy & paste)

    9. Click the Use Secure Connections box so that it is selected.
    10. Click OK, then OK again in the next window, then again in the next.

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Finding out more about Thunderbird

Mozilla's own support website for Thunderbird is probably your best source of information, at

created on 2011-09-13 by Andy Clews
last updated on 2020-01-06 by Paul Ryan