How To Configure Thunderbird For 0365

Thunderbird is an email client by Mozilla. Therefore, it lacks the support of Microsoft 0365 Exchange. If you prefer using Thunderbird you can configure it with IMAP to access it via Penn Microsoft 0365. It is important for your Local Support Provider (LSP) to review the issues below and judge whether a deployment makes sense for their unit.

As of Thunderbird version 78.4.1, OAuth2 is supported. Here's how to configure Thunderbird to provide IMAP account access to O365 using OAuth2 ("Modern Authentication" in Microsoft parlance).

  1. Tools > Account Settings > Account Actions > Add Mail Account...
  2.  Provide: Name, Email address (yourpennkey@upenn.edu), and O365 password, and click Continue
  3. After "Authentication failed" click Configure manually
  4. Provide these IMAP settings:
    • Server: outlook.office365.com
    • Port: 993
    • SSL: SSL/TLS
    • Authentication: OAuth2 (if listed), otherwise Normal password (will fail the first time)
    • Username: yourpennkey@upenn.edu
  5. Provide these SMTP settings:
    • Server: smtp.office365.com
    • Port: 587
    • SSL: STARTTLS
    • Authentication: Normal password
    • Username: yourpennkey@upenn.edu
  6. Click Re-test, and if it fails (because OAuth2 wasn't available as Authentication in step 4 or 5), change it now for BOTH IMAP and SMTP and click Done.
  7. In the browser window that appears, provide your password (again) and do the second-factor authentication.
  8. On your first attempt to send an email, Thunderbird may prompt you to provide a certificate to authenticate to the SMTP server, providing a list of the certificates in your computer's keyring. Click the "cancel" button at this prompt, and you'll be able to send it normally.