Microsoft Outlook: Adjust Junk Filtering

Many email servers have spam filtering which will either quarantine messages (eg some IMAP/POP hosting) or send them directly to the mailbox's Junk folder (eg. Microsoft 365 Exchange Online). But Microsoft Outlook itself has a spam filter which can contribute to whether items remain in the Inbox or go to Junk, and how agressively.

To configure this:

1. Right-click on any message (not necessarily spam) and choose Junk → Junk E-mail Options:
   

2. Under the Options tab, increase or decrease the filtering as required: