Thunderbird FAQ

**Currently there is a known issue where IPV6 needs to be disabled in the Thunderbird client in order to function properly**

Please note these instructions are best effort and ITS does not provide technical support for Thunderbird.

Download Thunderbird

You can obtain a free download of Thunderbird from the Mozilla website. Follow the instructions on the site for installing Thunderbird. These instructions require Thunderbird version 78 or later.

Set up a account in Thunderbird

After installing Thunderbird you need to configure it for use with your @NU mailbox.

  1. Launch Thunderbird and make sure you are in the account setup page.
  2. Enter your name as you want it to appear in the From field in outgoing mail and your email address. Then, click Continue.
  3. Thunderbird will attempt to automatically configure your account settings. This will fail and a message saying "Thunderbird failed to find the settings for your email account" will display. Enter the following settings (all settings except Authentication type may be accurate) :
    • IMAP
    • Server hostname:
    • Port: 993
    • SSL: SSL/TLS
    • Authentication: Oauth2


    • Server hostname:
    • Port: 587
    • Authentication: Oauth2

    Username (Incoming and Outgoing): your
    Note:  If you do not have OAuth2 as an authentication choice you can click the Re-test button after filling in the server information.

  4. Click Done. The Thunderbird main window displays.
  5. You should be prompted to complete the normal web-based two-factor authentication process.

Additional account settings

We recommend that you configure your Thunderbird to move your deleted messages to the Deleted Items folder on the server (webmail).  This setting allows you to recover deleted items. We also recommend keeping sent messages and drafts in the Sent Items and Drafts folders in webmail folders on the server. This will make it less confusing if you also use webmail or another email client to access your Office 365 email.

  1. Right-click your @NU account name and click Subscribe.
  2. Make sure the  Deleted Items, Drafts, and Sent Items folders (and any other folders you want to access in Thunderbird) are selected and then click Subscribe.
    Note: Do not subscribe to the Calendar folder.
  3. Click your @NU account name to display the Thunderbird main window. Under Accounts, click View settings for this account.
  4. In the Accounts Settings window, click Server Settings in the left panel. In the Server Settings section of the window,  When I delete a message, select Move it to this folder and then choose the Deleted Items folder on the server.
  5. Click Copies and Folders in the left panel and make the following changes:
    • When sending messages automatically, place a copy in: select Other and choose the Sent Items folder on the server.
    • Keep message drafts in: select Other and choose the Drafts folder on the server.
  6. Click Junk Settings in the left panel.
  7. Uncheck the box for Enable adaptive junk mail controls for this account.
    Note: Server side junk/spam filtering is already enabled for Office 365 accounts.
  8. Click OK to save your changes and close the Account Settings window.

Known issues

The following are known issues with Thunderbird:

  • When sending mail, Thunderbird may hang on the step "Copying Mail to Sent folder."
  • You may see an error message that says, "Error copying mail to Sent folder" with a prompt to retry.

To resolve these issues:

  1. In Thunderbird, go to the Tools menu and click Accounts Settings.
  2. In the left panel, click Server Settings.
  3. In the Server Settings section of the window, click the Advanced button.
  4. Change the Maximum number of server connections to cache to 1 and then click OK.
  5. Click OK to close the Account Settings window.