Configure Exchange Online with the Owl for Exchange add-on in Thunderbird

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Due to enhanced security features in Exchange Online, you should no longer use digital signatures at IU. Follow the appropriate instructions to remove your certificates.
The Owl for Education add-on is free to use for a one-month trial period. Use beyond the trial period requires procurement of a license from the vendor. Owl (Beonx) will not accept any purchases made with a university P-Card. Before initiating a personal software purchase, consult with your fiscal officer for personal purchase approval for reimbursement and your IT Pro.

To connect to Exchange Online at IU using Owl for Exchange in Thunderbird, follow these instructions. These steps have been tested on Windows, macOS, and Linux (specifically Debian) using Thunderbird 78.

Add Owl for Exchange to Thunderbird

To add and enable the Owl for Exchange add-on in Thunderbird:

  1. In Thunderbird, click Tools, and then select Add-Ons.
  2. In the search box, search for owl to find the Owl for Exchange add-on, and then click the corresponding Add to Thunderbird icon.
  3. When prompted to add Owl for Exchange, click Add, and then click OK.

Add your Exchange Online account

To add your IU Exchange Online account:

  1. Return to the Add-ons Manager tab, click Extensions, and find Owl for Exchange in the list of enabled extensions.
  2. Click the corresponding Add-on options icon (a wrench).
  3. Select Add new account manually, and then:
    • Your name: Enter your name as you would like it displayed.
    • Your email address: Enter your primary IU email address.
    • Your username: Enter (replace username with your IU username).
    • Protocol: Select Outlook Web Access.
    • Login method: Select Open login web page.
    • Webmail page: Enter
  4. Click Create account.
  5. When prompted, confirm your identity with Two-Step Login (Duo).
    If you are not prompted to authenticate with Two-Step Login (Duo), and you see an error that says "We're sorry, access is not allowed because you are not enrolled. Please contact your organization's IT help desk for assistance", you'll need to enroll a device in Duo before you can proceed. For more, see Get started with Two-Step Login (Duo) at IU.

If you try to send a message immediately after adding your account, you may get the following error (or something similar):

Sending of the message failed.

The server is overloaded. (This operation exceeds the throttling budget for policy part 'LocalTime', policy value '0', Budget type: 'Owa'. Suggested backoff time 171572 ms.)

If you receive this error, wait five to 10 minutes, and then try to send your message again.

Secondary accounts

It is not possible to directly add secondary IU Exchange Online accounts (for example, group accounts) with Owl using their credentials. This will generate a "You already have an Outlook on the web account with this hostname" error. However, "Full Access" and "Send As" rights, as well as delegate access, will work using the Owl for Exchange add-on.

  • If a secondary account is added as an additional account via Outlook on the web (so that it appears in the Folder menu when you are logged into Outlook on the web via your IU Exchange Online account, as described in Add the shared mailbox so it displays under your primary mailbox), it also will appear in Thunderbird in the Folder menu when you are logged into Exchange Online with Owl. "Full Access" rights and delegate access can be used to grant the ability to view a secondary account in this manner.
  • "Send As" rights will work when sending a message. To change the sender address, in the new message window, click the From field, and then select Customize From Address, and then enter the email address for which you have "Send As" rights.
  • Delegate access also can be used to send messages "on behalf of" others, using the same method described above. The only difference is that "Send As" rights will make messages appear as if they were sent directly from the secondary account, whereas delegate access will show messages as being sent "on behalf of" the secondary account.

Known issues and unknowns

  • Shared calendar access is not supported.

This is document hoot in the Knowledge Base.
Last modified on 2023-08-11 17:20:04.