How does Outlook's Junk Email filter work?

Outlook's Junk Email filter uses SmartScreen technology to evaluate incoming messages across multiple dimensions.

Sender reputation is evaluated through Microsoft's extensive databases. IPs and domains with poor history face heightened scrutiny. New senders without reputation face suspicion by default.

Authentication verification checks SPF, DKIM, and DMARC. Failures increase spam probability. Microsoft has increasingly enforced authentication requirements.

Content analysis scans for spam patterns, suspicious links, and characteristics associated with unwanted mail.

User signals including spam reports from other users influence filtering. If many users report a sender, that affects everyone's filtering.

Users can configure personal settings including safe and blocked sender lists that override SmartScreen decisions for their account.

SmartScreen is Microsoft's guardian. It combines technical analysis with collective user intelligence to protect inboxes.