Hi Reinhard and thanks for reaching out. There is a workaround for using a shared mailbox with the email connector by setting a password in AAD for the mailbox and logging in with those credentials. When a shared mailbox is created in AAD then a corresponding user is also generated for that mailbox. That user’s password can be reset using the Azure Portal User’s blade which would allow logging in as the shared mailbox to setup the email connector in Tikit.
Please let me know what you think. Thanks!