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Configure Thunderbird for use with MIT Microsoft 365 Mailboxes

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Office365 Setup Procedure

Office365, and other modern mail providers such as Gmail, are moving towards using authentication methods that support two-factor authentication. Often this means using OAUTH2.

MIT's Office365 environment supports OAUTH2 authentication for IMAP, but we do not support this for SMTP. All SMTP is handled via as normal.

Thankfully Thunderbird added support for OAUTH2 in v. 77 (or v. 78 ESR).

  1. If this is the first time you are running Thunderbird, you will be greeted by the add account prompt.

    Otherwise, go to Edit > Account Settings (or hamburger menu > Account Settings), then click Account Actions then Add Mail Account.

  2. Enter in your email address and password.

    Click on Configure Manually, and enter in the following server data.

    Setting Value
    Incoming server
    Port 993
    Connection type SSL/TLS
    Authentication OAuth2
    Username Full MIT email

    Setting Value
    Outgoing server
    Port 465 or 587
    Connection type SSL/TLS
    Authentication Normal password
    Username MIT/kerb username

  3. Hit Done.

  4. A Touchstone authentication window will open.

    Log in as normal.

  5. Then grant Thunderbird full permissions to your email.

    You are all set!
Make sure to change to Sent folder to Sent Items, and set up calendar and contact syncing! See relevant sections below.

Recommended Post Setup Tasks

Sent Folders

By default most IMAP clients will use the "Sent" folder to save sent email. Microsoft however uses the convention "Sent Items". To save yourself some confusion and heartache later, you should set Thunderbird to respect this convention.

  1. Go to Edit > Account Settings, then go to Copies & Folders under your MIT email account.

  2. Under When sending messages, automatically: select the Other radio button, then in the drop down navigate to the Sent Items folder for your MIT email (note: not a local folder.)

Set Mail Sync to "Online Only" Mode

The default behavior in Thunderbird is to download a local copy of all email. If you do not want this to happen, you can achieve this like so:

  1. Go to Edit > Account Settings, then go to the Synchronization & Storage section under your MIT email account.

  2. Untick the option Keep messages in all folders for this account on this computer

Signing Email with Personal SSL Certificates

It is possible to use your personal MIT certificates to digitally sign your emails. This is generally only useful if others have the MIT CA certificate installed on their systems to validate your signature, and if your recipients are expecting messages from you to be signed.

  1. First you need to download a copy of your personal SSL certificate: either use Firefox to access, or use any browser with

    Download a copy of your cert and remember the download password you set.

  2. Import this certificate into Thunderbird. Go to Edit > Preferences (or hamburger menu > Preferences), then to Privacy & Security, and scroll down to Certificates and click on Manage Certificates

  3. On the Your Certificates tab click on Import..., and select the certificate file you downloaded. At this stage you will need to enter in the download password you set before.

  4. Now you can pick this certificate to be used for signing or encryption. Go to Edit > Account Settings, then to End-To-End Encryption under your MIT email account.

  5. In the S/MIME section select your personal certificate.

  6. If you want you can also set signing email to be the default behavior. Otherwise you can do this per-message under the Options menu.

Additional Notes

Folder Subscriptions

If you do not see all the mail folders that you expect to see or if it looks like folders are missing, check to see that all of your folders are marked as "subscribed".

  1. Right-click your Inbox folder and choose Subscribe... from the menu.
  2. In the Subscribe window, put a checkmark on every folder that you want to appear in your folder list.
    Folders without checkmarks will be hidden and will not appear.


Documentation and information provided by the MIT Community

Last Modified:

February 02, 2024

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