1. In Thunderbird, go to Tools > Account Settings.
  2. Click Account Actions at the bottom.
  3. Click Add Mail Account
  4. Enter your full name (it will be used when sending emails from this account), your full BU email address, and your Kerberos password. Click Continue.
  5. Authentication will likely fail at first. A new box with Your login, will appear.  Enter your full BU email address again.
  6. Use Configure manually on the Thunderbird client to open server settings. You will be prompted to enter your server settings.

    7. Incoming Server

    • Incoming Server Protocol:  IMAP
    • Server/Host Name: outlook.office365.com
    • Port: 993.
    • Leave the remaining information as is – for now.

    Outgoing Server

    • Hostname may have a default value. Clear this field.
    • Client on Advance config
    • A pop-up will appear asking to confirm that you wish to proceed to advanced configuration; click OK. This step is needed because the Authentication Method needed (OAuth2) is not available in the manual configuration server settings drop-down menu.
    • Connection Security:SSL/TLS
    • Authentication Method: OAuth2

    Server Settings

  7. These settings should automatically be saved
  8. Close Tools/Preferences and go back to the inbox tab/window.
  9. Click on Inbox underneath the BU account. After a second of loading, the BU ADFS sign-in page will load in a mini-browser/kiosk window. BU email address is pre-filled. Enter Kerberos password and click Sign in.
  10. You will get a Duo prompt. Authenticate through Duo as you normally would. You do not need to check the Remember me for 30 days because the mail app will remember your account information.
  11. If you are asked to remain signed in, select No as the app will remember your account information/stay signed in.
  12. There may then be another prompt for “Permissions requested” Thunderbird would like to: follow a list of access items. Click Accept to proceed.
  13. The mini-browser window will close. If your emails do not start loading automatically, click on Inbox again to trigger a sync request.