Add shared Exchange Online Mailbox to Mail app

With Microsoft removing Basic Authentication in Exchange Online on 01.10.2022 (), they remove the ability to add a shared mailbox e.g. via IMAP or POP. (see e.g. or ) Several attempts with different email / user combinations failed either with the Mail app trying to add the sign in mail account (again) or with an 'Unable to verify user or password' error. Is it possible to add shared exchange mailboxes to the Mail app? If so, how? **EDIT:** I am running macOS Big Sur (11.6.6) and Mail.app version 14.0.