On rare occasions you may experience that spam messages are (consistently) delivered to the Inbox folder instead of the Junk E-mail folder even though it is rated at SCL: 9
The graphic below shows the properties of an e-mail rated at SCL: 0 as an example.
If you get mails with SCL level 5-9 in your inbox even though you enabled junk e-mail filtering in Outlook as shown below:
Then open OWA Settings, disable filtering and click save. Then re-enable filtering and save.
Now spam should go to your Junk E-mail Folder…