What’s the difference between global and user-level filtering?

Global filtering applies rules uniformly across all users of a mailbox provider. These rules block known spam campaigns, enforce authentication requirements, and query blocklists. If a sender is globally blocked, no user at that provider receives their mail.

User-level filtering personalizes decisions based on individual behavior. If you frequently open emails from a sender, your filter learns to prioritize them. If you consistently delete without reading, the filter may demote that sender to spam for you specifically.

Gmail heavily emphasizes user-level signals, which is why the same sender can land in the inbox for one recipient and spam for another. Outlook uses similar personalization through its Focused Inbox feature.

The combination creates a layered system. Global rules set the baseline. User-level signals fine-tune placement for each individual.

Global filtering is the lighthouse warning all ships away from the rocks. User-level filtering is each captain's personal log of trusted traders.