Outlook on the web (previously known as OWA) in Microsoft Exchange Server 2019 or Exchange Server 2016 still exposes junk operations to the UI partly. This issue occurs when an OwaMailboxPolicy is configured and junk email management is disabled through the parameter JunkEmailEnabled $false within the OwaMailboxPolicy. That means the Outlook on the web only removes the “Move to Junk” options partly and hides the Junk Email folder but not for the Navigation Pane.
To fix this issue, install one of the following updates:
For Exchange Server 2019, install the Cumulative Update 5 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.For Exchange Server 2016, install the Cumulative Update 16 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.