1. Open Thunderbird mail client
2. File / New / Existing Mail Account
3. Put your data, for example for me:
- Your name: Hubert Suder
- Email address: firstname.lastname@example.org
- Password: my_password_here
4. Press Continue, next "Manual Config" button. and make same configuration like me. Ask me only about "server hostname", which in the example image is blurred.
5. Press Done, and your company mailbox is ready to use.