How do Outlook's spam filters work (generally)?

Outlook.com and Exchange Online rely on authentication results IP reputation spam signatures content heuristics and user level feedback. Microsoft places strong emphasis on Spam Confidence Levels and bulk complaint rates.

Their core filtering engine is Microsoft SmartScreen which evaluates global patterns. For business and enterprise mail the filtering layer is known as EOP or Exchange Online Protection. This is why B2B delivery to Microsoft hosted domains often behaves differently from consumer Outlook traffic.

Outlook favors predictable senders with clean infrastructure and solid authentication.

It functions like a port authority inspecting cargo with both historical logs and modern scanning equipment.