To access and review quarantined messages in a shared mailbox, follow these steps:
1. Go to https://security.microsoft.com/quarantine
2. If you are not logged in, sign in with your own account.
3. Click the filter icon.
4. Enter the shared mailbox email address in the Recipient address.
5. Click Apply.
You will now see any quarantined messages in the shared mailbox.
Important: Be careful when reviewing and releasing quarantined messages, as many were flagged as potentially harmful.