Outlook 2016 and Norton

Hi

Looks like this problem has been rumbling on for years with no resolution in sight...

I have:

Windows 10 Home
Outlook 2016
Norton 22.9.4.8

The Outlook account is set to IMAP, not POP. I wish to continue using IMAP to allow access and control from multiple devices.

Norton AntiSpam seems to have killed all spam/junk email filtering. I am now receiving emails from senders in the Outlook blocked list.

I have turned off Norton AntiSpam and removed the Norton add-in from Outlook, rebooted, but the problem persists. Spam/junk email is no longer being filtered out as it was up until I installed Norton.

What's the solution please?

Thanks
Tommy.