Office 365, Email, Exchange, Thunderbird

Mozilla Thunderbird is a free and open-source email, calendar, and newsfeed program developed by the Mozilla Foundation.

Technology Services does not officially support or recommend Thunderbird. University of Illinois email accounts are known to be able to send and receive messages after some specific configuration, though users should understand that Technology Services is only able to fully support the Outlook desktop software or Outlook website interface.

Thunderbird is not able to automatically detect the correct settings for University accounts, so check this manual configuration even if it appears that your account is already present in Thunderbird.

After changing these settings, changing your University account's password, or updating Thunderbird, you may see an "Authentication failure" warning. If this occurs, close Thunderbird and then re-launch it; you will usually be shown an authentication popup window, asking you to enter your password again.

Navigate to the Account Settings menu by way of the Tools menu, the triple-bar in the upper right, or the gear icon in the lower left.

Server Settings

The side panel of the Account Settings screen will have a heading of your University email address; under this heading, click Server Settings and input the following:

  • Server Name:
  • Port: 993
  • User Name: your full University email address
  • Connection security: SSL/TLS
  • Authentication method: OAuth2

Outgoing Server (SMTP)

The side panel of the Account Settings screen will have an entry for Outgoing Server (SMTP); click this, then select your University account from the list, then click Edit... and input the following:

  • Server Name:
  • Port: 587
  • Connection security: STARTTLS
  • Authentication method: OAuth2
  • User Name: your full University email address


The above settings have been verified to function in Thunderbird versions 91 and 102 running on Windows 10, but should be valid for any version 78 or later on any operating system. There are some caveats to using Thunderbird with your University account:

  • the OAuth2 authentication method may not appear until after the office365 Server Name is input; if OAuth2 does not appear as an option in the 'authentication method' drop-down, try closing and reopening Thunderbird
  • the first time Thunderbird tries to send or receive mail with the OAuth2 protocol, it will produce a popup with a University-branded page prompting for your password; input it to reach a page asking for permissions. Thunderbird will not function properly unless you click the Accept button on this permissions page
    • if the password field goes blank instead of proceeding to the permissions page, turn on Accept cookies from sites in Thunderbird's Privacy settings
  • Thunderbird will not retrieve inbox subfolders that already exist, but seems to be able to create and upload them.
  • Technology Services Help Desk consultants do not use or support Thunderbird, and will not be able to provide support beyond the information on this page; we strongly recommend that you use the Outlook web interface, or the installed desktop software if your account is licensed for it. 
  • Thunderbird occasionally returns an error about IMAP configuration or "User authenticated but not connected" - this is due to a Thunderbird bug observed in version 102, but fixed in recent beta versions. The bug can be circumvented by disabling IPv6 connections, as described in these forum posts. We are not able to provide support beyond this.

Keywords:Exchange, email, calendar, Thunderbird, IMAP, SMTP, port, STARTTLS, migrations, office 365, A1, Linux   Doc ID:47659
Owner:Jackson M.Group:University of Illinois Technology Services
Created:2015-02-26 12:10 CDTUpdated:2023-08-28 10:17 CDT
Sites:University of Illinois Technology Services
Feedback:  15   7