Replace MS Outlook with Thunderbird when you need MS Exchange connectivity - ScottRFrost/scottrfrost.github.io GitHub Wiki

If you don't know your company's OWA URL, you can find it by clicking File > Info in the Windows Outlook app.

Install & Run Thunderbird.
In Thunderbird, Skip any intro screen and click Menu, then Addons. Search for and install the "Lightning" addon, then restart Thunderbird.
This time, click "Use my existing email" on the intro screen. Fill in your name, email address, and Active Directory / Exchange password, then click "Continue".
As soon as it starts searching for settings, override it by clicking "Manual Config".
In the manual configuration section, enter the following:

Incoming type: IMAP, server: localhost, port: 1143, SSL: none, Auth: Normal Password.
Outgoing type: SMTP, server: localhost, port: 1025, SSL: none, Auth: Normal Password.
Username: Your Active Directory / Exchange username in the format DOMAIN\Username.

Click "Re-Test", then "Done" and accept any SSL warnings that either of those produce.
Back on the Thunderbird main screen, you should see your emails starting to download. Click Menu > The Arrow to the Right of New Message > Calendar. Enter the following:

Locate your calendar: On the Network, Click "Next".
Format: CalDAV, Location: http://localhost:1080/users/[email protected]/calendar, Click "Next".
Name: Exchange, Color: Your Choice, Click "Next" and fill in your username (DOMAIN\username) and password.

Back on the Thunderbird main screen, click address book from the toolbar, then click file > New > LDAP Directory. Use the following settings:

Name: Exchange, Hostname: localhost, Base DN: ou=people, Port Number: 1389
Bind DN: Your Active Directory / Exchange username in the format DOMAIN\Username, Click "OK"

Do a search and it should ask for your password.
Click on Menu > Preferences and go to the Composition tab, then the Addressing sub-tab. Check "Directory Server" and then click "Close"