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Steps to add your corporate email account with Thunderbird on Windows, Mac and Linux. Written for current Thunderbird versions. Screenshots show the Turkish interface.
All the values you will use during setup are below. Replace yourdomain.com with your own domain name; the username is always your full email address, not just the "name" part.
The step-by-step email setup wizard asks for your email app and address, then guides you through every screen with settings tailored to your address. We never ask for your password.
Thunderbird tries to guess the settings; for corporate addresses, manual configuration is safer.

When you first open Thunderbird, the account setup screen appears right away. If you already use the program, follow Add account > Email from the three-line menu at the top right. (In older versions this path appears as New > Existing Mail Account.)

Fill in the two fields. Do not press the Continue button; click the Configure manually link just below it. This way you enter the correct server details yourself instead of Thunderbird trying to guess.

Leave the protocol as IMAP (choose POP3 if you only want to keep mail on a single computer). When you type the server name and enter the port, the connection security usually becomes SSL/TLS by itself; if not, select it manually. The username is your full email address.

When you click Continue, the outgoing server screen appears. Enter the same server name, set the port to 587 and choose Normal password as the authentication method. If this field is left empty, you can receive mail but not send it.
When you click Continue, Thunderbird connects to the server and asks for your password. Enter the password and tick the Remember password option. After the account is created, send yourself a test email and check whether you receive it.
The server details are the same in all of them; only the look of the screens changes.
Outlook 365 and the new Outlook app
Classic Outlook versions (2013-2021)
iOS and iPadOS Mail app
Android phones and tablets
The Mail app on Mac